Refrigerator

ABSTRACT

A refrigerator equipped with a door that becomes transparent as necessary to make the interior thereof visible is disclosed. The refrigerator includes a cabinet having a storage compartment defined therein, a lighting device for illuminating the interior of the storage compartment, a door, which is hingedly coupled to the cabinet to open and close the storage compartment, and has an opening and a panel assembly including a front panel disposed on the front surface thereof, a sensor for detecting sound waves, which are generated by a knock input applied to the door and are transmitted through the front panel, and a controller for controlling the lighting device to allow light to be transmitted through the panel assembly, thus making the storage compartment visible from outside the door through the opening when a predetermined knock input is detected.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is continuation U.S. application Ser. No. 15/306,862,filed on Oct. 26, 2016, which is a U.S. National Phase Application under35 U.S.C. § 371 of International Application PCT/KR2015/011029, filed onOct. 19, 2015, which claims the benefit of Korean Application No.10-2014-0140936, filed on Oct. 17, 2014, Korean Application No.10-2014-0181403, filed on Dec. 16, 2014, and Korean Application No.10-2015-0088477, filed on Jun. 22, 2015, the entire contents of whichare hereby incorporated by reference in their entireties.

TECHNICAL FIELD

The present invention relates to a refrigerator equipped with a doorthat becomes transparent as necessary to make the interior thereofvisible, and more particularly, to a refrigerator equipped with a doorthat becomes transparent as necessary to make the interior thereofvisible without having to open the door.

BACKGROUND ART

In general, refrigerators are apparatuses for keeping foods frozen or ata temperature slightly above freezing temperature by discharging coldair generated by a refrigeration cycle consisting of, for example, acompressor, a condenser, an expansion valve, and an evaporator to lowerthe temperature in a storage compartment thereof.

A typical refrigerator includes a freezing compartment, in which foodsor beverages are kept frozen and a refrigerating compartment, in whichfoods or beverages are kept cold.

There are several kinds of refrigerators, including a top-mounting typerefrigerator, in which a freezing compartment is located above arefrigerating compartment, a bottom-freezer type refrigerator, in whicha freezing compartment is located below a refrigerating compartment, anda side-by-side type refrigerator, in which a freezing compartment and arefrigerating compartment are respectively located on left and rightsides. The freezing compartment and the refrigerating compartment may beprovided with respective doors, and may be accessed through therespective doors.

In addition to such refrigerators, which include a refrigeratingcompartment and a freezing compartment which are compartmentalized fromeach other, there is also a refrigerator which allows access to both therefrigerating compartment and the freezing compartment through a singledoor. This kind of refrigerator is mostly small-sized, and is typicallyconstructed such that the freezing compartment is provided in apredetermined space within the refrigerating compartment.

Among the top-mounting refrigerators, there is also provided a Frenchtype refrigerator in which an upper refrigerating compartment is openedand closed by right and left doors. The freezing compartment of theFrench type refrigerator may also be opened and closed by right and leftdoors.

Recently, in addition to the original function of keeping foodsrefrigerated or frozen, the variety of functions provided byrefrigerators is increasing. For example, a dispenser is installed to adoor of the refrigerator to provide purified water and ice, and adisplay is installed on the front surface of the door to show the stateof the refrigerator and to assist a user in controlling therefrigerator.

The door of a refrigerator is generally constructed to be opaque and toopen and close the storage compartment of the refrigerator body. Inother words, the door also serves as a thermal insulating wall thatdefines a refrigerating compartment or a freezing compartment. Thedifference resides in the fact that the door is a kind of thermalinsulating wall that is capable of being opened and closed so as toallow a user to access to the refrigerating compartment or the freezingcompartment. Accordingly, it is typical for a user not to know the type,location, etc. of objects stored in the storage compartment beforeopening the door.

A large amount of cold air is lost when the door of a refrigerator isopened. Accordingly, the loss of cold air accumulates as the doorremains in the opened state.

Generally, objects having various shapes are stored in the refrigeratingcompartment of the freezing compartment. Accordingly, it typically takesa user a rather long time to find and take out a desired object.Specifically, a considerable time is required for the user to look allaround the storage compartment and find a desired object in the state inwhich the door is opened.

That is, the inherent characteristics of the refrigerator inconveniencethe user and lead to increased energy consumption.

In recent years, a refrigerator in which only part of a storagecompartment is opened has been proposed. For example, a refrigeratorwhich is provided with a sub door for opening and closing a sub storagecompartment defined in a main door has been proposed. The sub storagecompartment is a portion of the space of the main storage compartment,and is isolated from the main storage compartment by a partition wall.This kind of refrigerator may be referred to as a door-in-door (DID)refrigerator. This DID refrigerator is advantageous in that the outwardleakage of cold air from the main storage compartment is considerablyreduced when only the sub door is opened.

For example, stored objects, such as beverages, which are frequentlytaken out of and put back into the storage compartment, are stored inthe sub storage compartment, and thus the sub storage compartment can beaccessed by opening the sub door while maintaining the main door in theclosed state.

There is also a home-bar refrigerator which is equipped with a home-bardoor. The home-bar may be considered a very small sized sub storagecompartment. Specifically, a small amount of beverages or the like maybe stored in the home-bar, which is provided in the rear of the maindoor through a home-bar door mounted in a very small area of the maindoor.

A refrigerator in which the home-bar is further enlarged, compared tothe home-bar refrigerator, may be referred to as the DID refrigerator.

However, the home-bar refrigerator and the DID refrigerator both havethe same problem in that the volume of the sub storage compartment andthe amount of objects stored in the sub storage compartment areincreased. In other words, it takes a considerable time to open the subdoor or the home-bar door and find an object to be taken out, which isinconvenient for the user and increases energy consumption.

DISCLOSURE Technical Problem

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the prior art.

In an embodiment, the present invention intends to provide arefrigerator equipped with a door for opening and closing a storagecompartment, which is at least partially transparent so as to make theinterior of the storage compartment visible without having to open thedoor.

In an embodiment, the present invention intends to provide arefrigerator equipped with a see-through door which allows light to betransmitted therethrough, that is, a refrigerator equipped with asee-through door which allows the interior of a storage compartmentbehind the door to be visible through the door from the outside.

In an embodiment, the present invention intends to provide arefrigerator equipped with a door capable of being selectively convertedinto a see-through door, that is, a refrigerator equipped with a doorthat normally does not allow a storage compartment to be visible throughthe door, but only allows the storage compartment to be visible whenrequired by a user.

In an embodiment, the present invention intends to provide arefrigerator which is constructed to enable a user to easily apply inputfor conversion into a see-through door and to reduce input error,recognition error, malfunctions, or the like, that is, a refrigeratorcapable of improving the recognition rate so as to correctly recognizeuser input.

In an embodiment, the present invention intends to provide arefrigerator capable of efficiently detecting a user's tapping, that is,a knock input for conversion into a see-through door, thus making iteasy to use.

In an embodiment, the present invention intends to provide arefrigerator capable of efficiently detecting a user's tapping even ifthe position (knock input position) at which the user taps is spacedapart from the position (knock detecting position) at which the tappingis detected.

In an embodiment, the present invention intends to provide arefrigerator in which the area of a door on which a user taps isexpanded to the entire front surface of the door by employing thetransmission of sound wave through a medium.

In an embodiment, the present invention intends to provide arefrigerator which is able to efficiently detect a knock input and issimplified in structure by eliminating expensive devices such as touchpanels.

In an embodiment, the present invention intends to provide arefrigerator which ensures reliable thermal insulation performance andstability and is easily fabricated.

In an embodiment, the present invention intends to provide arefrigerator equipped with a door which normally operates as an opaquedoor but serves as a see-through door by activating a lighting devicewhen required by a user, thus reducing the energy consumption requiredfor conversion into a see-through door.

In an embodiment, the present invention intends to provide arefrigerator in which the entire see-through area of a door is used asthe knock input area and a sensor for detecting a knock input is mountedon an area other than a see-through area so as to prevent the sensorfrom interfering with the see-through area, thus providing anaesthetically pleasing appearance.

In an embodiment, the present invention intends to provide arefrigerator in which a sensor for detecting a knock input is mounted onand in close contact with a panel to which a knock input is applied soas to efficiently detect a knock input and to prevent false detectioncaused by disturbances. In particular, the present invention intends toprovide a refrigerator which is able to maintain force sufficient tokeep the sensor in close contact with the panel.

In an embodiment, the present invention intends to provide arefrigerator in which the sensor detects a sound wave caused by a knockinput and is in close contact with the panel with a hermetical spacetherebetween, thereby efficiently detecting a knock input and preventingfalse detection caused by external noises.

In an embodiment, the present invention intends to provide arefrigerator which has a structure capable of causing a sensor fordetecting user input for conversion into a see-through door to becontinuously in close contact with a medium, thereby improving thedurability and reliability of the action of the refrigerator relating tothe see-through door.

In an embodiment, the present invention intends to provide arefrigerator having a door capable of being easily converted into asee-through door and ensuring reliable thermal insulation performance.Furthermore, the present invention intends to provide a refrigeratorwhich is easy to manufacture.

In an embodiment, the present invention intends to provide a door havingan aesthetically pleasing appearance and a refrigerator including thesame.

In an embodiment, the present invention intends to provide arefrigerator which is capable of preventing an aesthetically pleasingappearance from being deteriorated due to input unit for allowing inputfor conversion into a see-through door and a detection unit fordetecting such input.

Technical Solution

The object of the present invention can be achieved by providing arefrigerator including a cabinet having a storage compartment definedtherein, a lighting device for illuminating the interior of the storagecompartment, a door, which is hingedly coupled to the cabinet to openand close the storage compartment and has an opening and a panelassembly including a front panel disposed on the front surface thereof,a sensor for detecting sound waves, which are generated by theapplication of a knock input to the door and are transmitted through thefront panel, and a controller for controlling the lighting device toallow light to be transmitted through the panel assembly, thus makingthe storage compartment visible from outside the door through theopening when a predetermined knock input is detected.

The controller may activate the lighting device when it is determined bydetection by the sensor that two or more user knock inputs are appliedwithin an interval corresponding to a predetermined period of time. Theactivation of the lighting device enables the door to be converted intoa see-through door.

The controller may activate the lighting device to cause the storagecompartment to be gradually brightened when the lighting device isactivated. The controller may deactivate the lighting device after thelapse of a predetermined time since the lighting device was activated.

The controller may deactivate the lighting device when the sensordetects that a user taps on the door after the lighting device hasalready been activated.

When the knock inputs are continuously repeated, the controller maysequentially determine whether two continuous knock inputs are knock oninputs, and extends the activation time of the lighting device when itis determined that the two continuous knock inputs are knock on inputs.

When the knock inputs are continuously repeated, the controller mayalternately determine that the continuous knock inputs are knock oninputs or knock off inputs for deactivating the lighting device, and maycontrol the lighting device to be repeatedly turned on and off.

When the knock inputs are continuously repeated, the controller mayignore subsequent knock on input while the lighting device is activated.

The sensor may include a sensor device and a sensor device receptor foraccommodating the sensor device. Specifically, the sensor may include asensor device for detecting input for conversion into a see-through doorby a user and a sensor device receptor for mounting the sensor device onthe front panel. In other words, the sensor device may not be mounted onthe front panel directly, but may be mounted on the front panel via thesensor device receptor. The sensor device and the sensor device receptormay collectively be referred to as a sensor device module.

The sensor device may be a microphone for detecting sound waves.Accordingly, the sensor device receptor may be referred to as amicrophone receptor, and the sensor device module may be referred to asa microphone module.

The sensor may include a modular microcomputer which is providedindependently from the controller, and the modular microcomputer maydetermine whether a predetermined knock input is applied by detectinguser input received through the microphone, that is, whether a normaluser input is applied. The modular microcomputer may send the result ofthe determination to the controller.

When the sensor device is a microphone, the modular microcomputer maydetermine that a predetermined knock input is applied by detecting soundwaves received through the microphone, and may send the result of thedetermination to the controller.

The sensor may include a filter for removing noise from a signalreceived at the microphone module, an amplifier for amplifying a signaloutput from the filter and outputting the signal to the modularmicrocomputer, and a PCB on which the filter, the amplifier and themodular microcomputer are mounted.

The sensor may include a support member for accommodating the microphonemodule and causing the microphone module to closely contact the frontpanel.

The support member may include a holder, which accommodates the sensordevice module or the microphone module and which is biased to cause thesensor device module or the microphone module to closely contact thefront panel.

The support member may include an elastic element for supporting theholder from the rear of the holder.

The panel assembly may include the front panel, which is made of atransparent material and defines the appearance of the front of thedoor, and a thermal insulation panel, which is disposed behind the frontpanel and is mounted at the opening, wherein the microphone moduleclosely contacts the front surface or the rear surface of the frontpanel.

The door may include an inner frame having an opening and constituting amarginal portion of the door, and a door frame including a door liner,which is disposed behind the door frame and has an opening, the doorliner constituting a marginal portion of the door.

The panel assembly may be coupled to the door frame from the front ofthe door frame.

The thermal insulation panel may be fitted in the opening in the innerframe, and the front panel may be configured to be larger than thethermal insulation panel so as to cover the opening in the inner frame.

The front panel may be attached to the front surface of the door frame.

The sensor device or the microphone module may be disposed in the areabetween the opening in the inner frame and the marginal portion of thefront panel.

The door may include an upper cap decoration and a lower cap decoration,which are coupled to the upper portion and the lower portion of the doorframe, respectively, and one of the upper and lower cap decorations maybe provided with a through hole through which the microphone modulepasses, wherein the microphone module passes through the through holeand closely contacts the rear surface of the front panel.

The door may include an outer door having an opening and constituting amarginal portion of the door, a door liner disposed behind the outerdoor and having an opening, the door liner constituting the marginalportion of the door, and cap decorations respectively coupled to upperends and lower ends of the outer door and the door liner.

The panel assembly may be disposed between the outer door and the doorliner, and the outer door and the door liner may be coupled to eachother such that the marginal portion is covered by the outer door.

The microphone module may be disposed behind the outer door so as toclosely contact the front surface of the front panel.

In another aspect of the present invention, provided herein is arefrigerator including a cabinet having a storage compartment definedtherein, a main door, which is hingedly coupled to the cabinet to openand close the storage compartment and has an opening therein, a substorage compartment provided at the rear surface of the main door, alighting device for illuminating the sub storage compartment, a subdoor, which is hingedly coupled to the main door or the cabinet to openand close the sub storage compartment and includes a panel assemblyincluding a front panel disposed at the front surface thereof, amicrophone module for detecting input for conversion into a see-throughdoor applied by a user, and a controller, which, when a predeterminedinput is detected, activates the lighting device such that light istransmitted through the panel assembly so as to make the sub storagecompartment visible through the opening in the sub door from outside thesub door.

The sensor device module may be a microphone module for detecting inputfor conversion into a see-through door by a sound wave. The microphonemodule may include a microphone for detecting sound waves and amicrophone receptor for accommodating the microphone. The microphone maydetect sound waves transmitted through the front panel.

The input for conversion into a see-through door may be input whereby auser taps on the front panel, that is, a knock input. Accordingly, themicrophone may detect sound waves transmitted through the front panel.

In still another aspect of the present invention, provided herein is arefrigerator including a cabinet having a storage compartment definedtherein, a lighting device for illuminating the interior of the storagecompartment, a door, which is hingedly coupled to the cabinet to openand close the storage compartment and has therein an opening and whichincludes a panel assembly including a front panel disposed on the frontsurface thereof, a sensor including a sensor device module disposedoutside the opening in the radial direction to detect input, applied bya user, for conversion into a see-through door, and a controller, which,when a predetermined input is detected, activates the lighting devicesuch that light is transmitted through the panel assembly so as to makethe storage compartment visible through the opening in the door fromoutside the door, wherein the refrigerator further includes a supportmember for supporting the sensor device module so as to cause the sensordevice module to closely contact the front panel and to define ahermetical space between the support member and the front panel to blockexternal noise.

The sensor device module may include a sensor device, and a sensordevice receptor, which accommodates the sensor device, closely contactsthe front panel, and has a hermetical space therein.

The support member may include a holder, which accommodates the sensordevice module and is biased to cause the sensor device module to closelycontact the front panel.

The sensor device module may include a signal line extending outwardfrom the sensor device, and the holder may have a slot in which thesignal line is fitted such that the signal line extends outward from theholder.

The door may include a door frame, which has an opening and is coupledto the panel assembly, and the door frame may have a through hole,through which the holder passes and which closely contact the frontpanel radially outside the opening.

A holder mount on which the holder is mounted may be provided behind thethrough hole.

In yet another aspect of the present invention, provided herein is arefrigerator including a cabinet having a storage compartment definedtherein, a lighting device for illuminating the interior of the storagecompartment, a door, which is hingedly coupled to the cabinet to openand close the storage compartment and has an opening and which includesa panel assembly including a front panel disposed at the front surfacethereof, a sensor for detecting a knock input applied to the frontpanel, and a controller, which, when a predetermined knock input isdetected, activates the lighting device such that light is transmittedthrough the panel assembly so as to make the storage compartment visiblethrough the opening in the door from outside the door, wherein thesensor includes a microphone module for detecting sound waves, which aregenerated by a knock input of a user and are transmitted through thefront panel, and the microphone module closely contacts the front panelradially outside the opening so as to prevent the microphone module frominterfering with transmission of light through the opening.

The door may include a door frame, which has an opening and is coupledto the panel assembly, and the front face of the microphone module maybe covered by the door frame in order to prevent the microphone modulefrom being visibly exposed to the outside from the front surface of thedoor.

The door may include a door frame, which has an opening and is coupledto the panel assembly, and the front face of microphone module may becovered by the door frame, which is opaque when light is not transmittedtherethrough so as to prevent the microphone module from being visiblyexposed to the outside from the front surface of the door.

In still another aspect of the present invention, provided herein is arefrigerator including a cabinet having a storage compartment definedtherein, a lighting device for illuminating the interior of the storagecompartment, a door, which is hingedly coupled to the cabinet to openand close the storage compartment, has an opening therein, and includesa panel assembly including a front panel disposed on the front surfacethereof, a sensor for detecting input for, transmitted through the frontpanel by a user, for conversion into a see-through door, and acontroller, which, when a predetermined input is detected, activates thelighting device such that light is transmitted through the panelassembly so as to make the storage compartment visible through theopening in the door from outside the door, wherein the sensor includesthe sensor device module, which is disposed radially outside the openingand closely contacts the front panel.

The panel assembly may include a thermal insulation glass panel, whichis spaced rearward apart from the front panel and is mounted at theopening so as to define a hermetical thermal insulation space betweenthe thermal insulation glass panel and the front panel, and the sensordevice module may be positioned radially outside the hermetical thermalinsulation space and may be spaced apart from the thermal insulationglass panel.

In a further aspect of the present invention, provided herein is arefrigerator including a cabinet having a storage compartment definedtherein, a lighting device for illuminating an interior of the storagecompartment, a door, which is hingedly coupled to the cabinet to openand close the storage compartment and which has an opening therein, apanel assembly disposed on the door and selectively becomingtransparent, and a controller for controlling the lighting device tocause the panel assembly to become transparent, thus making the storagecompartment visible from outside the door through the opening.Accordingly, the panel assembly may be selectively converted into thetransparent panel, that is, the see-through door, by the control of thecontroller.

The panel assembly may cover the opening. That is, the panel assemblymay have a larger area than the opening. Both the panel assembly and theopening may be configured to have substantially rectangular shapes.Accordingly, the central area of the panel assembly may correspond tothe opening, and the marginal portion of the panel assembly may extendoutward beyond the opening.

The central area of the panel assembly, that is, the area correspondingto the opening, may be considered to be a see-through area. The interiorof the storage compartment may be visible from the outside through thesee-through area.

The panel assembly may constitute the door. Accordingly, it is criticalto ensure thermal insulation by the panel assembly. Accordingly, thepanel assembly may include a front panel provided at the front surfaceof the door and a thermal insulation glass panel, which is spacedrearward apart from the front panel so as to define a hermetical thermalinsulation space between the thermal insulation glass panel and thefront panel. The thermal insulation glass panel may have furtherimproved thermal insulation performance by virtue of the hermeticalthermal insulation space between the thermal insulation glass panel andthe front panel, in addition to its inherent thermal insulationcharacteristics. The hermetical space may be a vacuum space, or may be aspace filled with inert gas, such as argon, that has better thermalinsulation characteristics than air.

The sensor may be positioned outside the hermetical thermal insulationspace in a radial direction and may be spaced apart from the thermalinsulation glass panel. That is, the sensor may be positioned outsidethe hermetical thermal insulation space.

Accordingly, it is possible to fundamentally prevent a decrease inthermal insulation performance, and it is possible to easily mount thesensor after the creation of the hermetical thermal insulation space. Inother words, since the sensor may be mounted on the front panel in aclose-contact manner after fabrication of the panel assembly, it makesit easy to fabricate a door.

The thermal insulation glass panel may be constituted by a plurality ofglass panels, and a thermal insulation space may be defined between theplurality of glass panels.

The front panel may also be made of a glass material. Accordingly, lightcan be transmitted through the panel assembly by conversion into asee-through door, thereby enabling the interior of the storagecompartment to be visible by a user.

The front panel may be considered to be a component part that is exposedfrom the front surface of the door. The front panel may also beconsidered to be the component part to which input for conversion into asee-through door is applied. That is, it is possible to construct inputunit having a relatively large area. For example, the input unit canhave an area extending over substantially the entire front surface ofthe door, rather than having a very small area, as in a button.Accordingly, it is possible to realize input unit which extends oversubstantially the entire front surface of the door.

Since the conversion into a see-through door can be implemented bydetecting sound waves transmitted through the inside of the front panel,the input unit, which is pulled or pressed for the purpose of conversioninto a see-through door, may be obviated. Accordingly, the seal at themarginal region of the input unit (i.e. the front panel) may beefficiently maintained.

The door may include a door frame, which has therein an opening andconstitutes the marginal portion of the door. The door frame may includethe front door frame and the door line. The door liner may be positionedbehind the door frame, particularly the front door frame. The door linermay also have an opening, and may constitute the marginal portion of thedoor.

The panel assembly may be coupled to the front of the door frame. Thethermal insulation panel may be fitted in the opening in the door frame,and the front panel may be configured to be larger than the thermalinsulation panel so as to cover the opening in the door frame. The frontpanel may be attached to the front surface of the door frame.

The door may include an upper cap decoration and a lower cap decoration,which are coupled to the door frame at an upper portion and a lowerportion thereof, respectively.

Accordingly, the front panel may define the overall appearance of thefront surface of the door.

The door may include an outer door having an opening and constituting amarginal portion of the door, a door liner disposed behind the outerdoor and having an opening therein, the door liner constituting themarginal portion of the door, and cap decorations respectively coupledto upper ends and lower ends of the outer door and the door liner.

The panel assembly may be disposed between the outer door and the doorliner, and the outer door and the door liner may be coupled to eachother such that the marginal portion is covered by the outer door.

Accordingly, the appearance of the entire front surface of the door maybe defined by the outer door which is the marginal portion of the doorand the front panel which is the central portion of the door.

Advantageous Effects

According to an embodiment of the present invention, there is provided arefrigerator equipped with a door for opening and closing a storagecompartment, which is at least partially transparent so as to make theinterior of the storage compartment visible without having to open thedoor.

According to an embodiment of the present invention, there is provided arefrigerator equipped with a see-through door which allows light to betransmitted therethrough, that is, a refrigerator equipped with asee-through door which allows the interior of a storage compartmentbehind the door to be visible through the door from the outside.

According to an embodiment of the present invention, there is provided arefrigerator equipped with a door capable of being selectively convertedinto a see-through door, that is, a refrigerator equipped with a doorthat normally does not allow a storage compartment to be visible throughthe door, but only allows the storage compartment to be visible whenrequired by a user.

According to an embodiment of the present invention, there is provided arefrigerator which is constructed to enable a user to easily apply inputfor conversion into a see-through door and to reduce input error,recognition error, malfunctions, or the like, that is, a refrigeratorcapable of improving the recognition rate so as to correctly recognizeuser input.

According to an embodiment of the present invention, there is provided arefrigerator capable of efficiently detecting a user's tapping, that is,a knock input for conversion into a see-through door, thus making iteasy to use.

According to an embodiment of the present invention, there is provided arefrigerator capable of efficiently detecting a user's tapping even ifthe position (knock input position) at which the user taps is spacedapart from the position (knock detecting position) at which the tappingis detected.

According to an embodiment of the present invention, there is provided arefrigerator in which the area of a door on which a user taps isexpanded to the entire front surface of the door by employing thetransmission of sound waves through a medium.

According to an embodiment of the present invention, there is provided arefrigerator which is able to efficiently detect a knock input and issimplified in structure by eliminating expensive devices such as touchpanels.

According to an embodiment of the present invention, there is provided arefrigerator which ensures reliable thermal insulation performance andstability and is easily fabricated.

According to an embodiment of the present invention, there is provided arefrigerator equipped with a door which normally operates as an opaquedoor but serves as a see-through door by activating a lighting devicewhen required by a user, thus reducing the energy consumption requiredfor conversion into a see-through door.

According to an embodiment of the present invention, there is provided arefrigerator in which the entire see-through area of a door is used asthe knock input area and a sensor for detecting a knock input is mountedon an area other than a see-through area so as to prevent the sensorfrom interfering with the see-through area, thus providing anaesthetically pleasing appearance.

According to an embodiment of the present invention, there is provided arefrigerator in which a sensor for detecting a knock input is mounted onand in closed contact with a panel to which a knock input is applied soas to efficiently detect a knock input and prevent false detectioncaused by disturbances. In particular, there is provided a refrigeratorwhich is able to maintain the force that keeps the sensor in closecontact with the panel.

According to an embodiment of the present invention, there is provided arefrigerator in which the sensor detects a sound wave caused by a knockinput and is in close contact with the panel with a hermetical spacetherebetween, thereby efficiently detecting a knock input and preventingfalse detection caused by external noises.

According to an embodiment of the present invention, there is provided arefrigerator which has a structure capable of keeping a sensor, fordetecting user input for conversion into a see-through door, incontinuous close contact with a medium, thereby improving the durabilityand reliability of the action of the refrigerator relating to thesee-through door.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, illustrate embodiments of the inventionand together with the description serve to explain the principle of theinvention.

In the drawings;

FIG. 1 is a perspective view showing a refrigerator according to a firstembodiment of the present invention;

FIG. 2 is a perspective view showing the right door of the refrigeratingcompartment shown in FIG. 1, which is removed from the refrigerator;

FIG. 3 is a perspective view of the right door, which is cut away alongline IV-IV of FIG. 2;

FIG. 4 is an exploded perspective view of a sub door of FIG. 2;

FIG. 5 is a perspective view showing a refrigerator according to asecond embodiment of the present invention;

FIG. 6 is a perspective view showing the right door of the refrigeratingcompartment shown in FIG. 5, which is removed from the refrigerator;

FIG. 7 is a perspective view of the right door, which is cut away alongline VIII-VIII of FIG. 6;

FIG. 8 is an exploded perspective view of a sub door of FIG. 6;

FIG. 9 is a cross-sectional view showing a front panel and a thermalinsulation panel of the sub door according to the first embodiment,which are assembled with each other;

FIG. 10 is a graph showing the variation in temperature during a pumpingtype process, which includes welding, vacuum pumping and sealing, inmanufacture of the door;

FIG. 11 is a graph showing the variation in temperature during weldingand sealing processes performed in a vacuum chamber;

FIG. 12 is a block diagram showing a control construction according toan embodiment of the present invention;

FIG. 13 is a cross-sectional view of a microphone module (sensor devicemodule), which is applicable to the embodiment of the present invention;

FIG. 14 is a perspective view showing a structure for mounting a sensordevice module (microphone module) in the sub door according to the firstembodiment, which is partially cut away;

FIG. 15 is a fragmentary perspective view showing a structure formounting a sensor device module (microphone module) in the sub dooraccording to the second embodiment;

FIG. 16 is a perspective view showing the structure shown in FIG. 15;

FIG. 17 is an enlarged view showing a cap decoration having a throughhole formed therein in another embodiment of the structure for mountingthe sensor device module (microphone module) of the sub door accordingto the second embodiment;

FIG. 18 is a fragmentary perspective view showing the microphone modulemounted in the through hole shown in FIG. 17;

FIG. 19 is a perspective view of a cover coupled to the cap decorationshown in FIG. 17;

FIG. 20 a conceptual diagram illustrating the position on the sub dooron which the sensor device module (microphone module) is mounted and thearea on the sub door on which a user taps; and

FIGS. 21 to 23 are graphs illustrating the control logic of embodimentsof a control method performed in accordance with various continuousknock inputs.

BEST MODE

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings.

The embodiments of the present invention are not limited to theabove-mentioned type refrigerators. In other words, a main door adaptedto open and close a refrigerating compartment or a freezing compartmentmay be a see-through door, or a sub door adapted to open and close a substorage compartment or a home-bar door may be a see-through door. Sincea home-bar door is also hingedly coupled to the main door, such ahome-bar door may be alternatively referred to as a sub door.

FIGS. 1 to 4 are views showing a refrigerator according to a firstembodiment of the present invention. The refrigerator shown in thedrawings is a bottom-freezer type refrigerator in which a refrigeratingcompartment is provided at an upper position of a cabinet 10 and afreezing compartment is provided at a lower position of the cabinet 10.The refrigerating compartment or the freezing compartment may beconsidered part of the storage compartment or the main storagecompartment 11 defined in the cabinet 10.

As described above, the present invention is not limited to this type ofrefrigerator. The present invention may be applied to any type ofrefrigerator as long as the refrigerator includes a door for opening andclosing the storage compartment.

In the embodiment shown in the drawings, a left refrigeratingcompartment door 20 and a right refrigerating compartment door 25, whichserve as doors for opening and closing the refrigerating compartment,are hingedly coupled to the left side and the right side of the cabinet10. Alternatively, a single refrigerating compartment door may behingedly coupled to the cabinet 10.

The left refrigerating compartment door 20 is an opaque door including ahandle groove provided at the lower end thereof. In contrast, the rightrefrigerating compartment door 25 selectively becomes transparent suchthat a user can see the interior through the door 25. In other words,the right refrigerating compartment door 25 may be embodied as asee-through door.

Freezing compartment doors, which are provided under the refrigeratingcompartment door, may also include a left freezing compartment door 30and a right freezing compartment door 40, which are hingedly coupled torespective sides of the lower portion of the front surface of thecabinet 10. Alternatively, a single freezing compartment door may behingedly coupled to the cabinet 10, or a drawer type door may be mountedin the cabinet 10 so as to be pulled forward from the cabinet 10 andpushed rearward into the cabinet 10.

The left freezing compartment door 30 may be provided at the uppersurface thereof with a handle groove 32, and the right freezingcompartment door 40 may also be provided at the upper surface thereofwith a handle groove.

Referring to FIG. 1, an embodiment in which some of the doors areembodied as see-through doors is shown. However, any door, which can beprovided at a refrigerator, may be embodied as a see-through door,regardless of whether it opens and closes a refrigerating compartment ora freezing compartment, and regardless of whether it opens and closes amain storage compartment or a sub storage compartment.

As shown in FIG. 1, the right refrigerating compartment door 25 mayinclude a main door 100, hingedly coupled to one side of the cabinet 10by means of a main door hinge 110, and a sub door 200, hingedly coupledto the main door 100 or the cabinet 10 by means of a sub door hinge 100.In other words, the refrigerating compartment may be accessed by openingboth the main door 100) and the sub door 200.

The main door 100 may be provided at the center with an opening, and maybe provided at the back surface thereof with a sub storage compartment(not shown).

Accordingly, when the sub door 200 is opened, the sub storagecompartment may be accessed through the opening in the main door 100. Inother words, a user can access the sub storage compartment by openingonly the sub door 200 without having to open the main door 100.

The sub storage compartment may be defined by a plurality of baskets(not shown) installed at different levels. Specifically, a cover (notshown) adapted to surround the plurality of baskets may be provided. Thecover may serve as a partition wall for isolating the sub storagecompartment and the main storage compartment from each other.Accordingly, the sub storage compartment may be positioned in front ofthe main storage compartment.

As shown in FIG. 2, a plurality of mounting protrusions 120 for mountinga plurality of baskets (not shown) may be provided at rear regions ofthe inner surfaces of the opening 115 in the main door 100. Theplurality of baskets may be two or three baskets, which are verticallyspaced apart from each other by predetermined distances. Accordingly, auser can access the sub storage compartment by opening the sub door 200while leaving the main door 100 closed. When the sub door 200 is openedtogether with the main door 100, the sub storage compartment 111 is, ofcourse, rotated together with the main door 100. Therefore, a user canaccess the main storage compartment provided behind the sub storagecompartment 111.

Since the relationship between the main door and the sub door and therelationship between the main storage compartment and the sub storagecompartment are common in a DID refrigerator, descriptions thereof areomitted.

The sub door 200 is internally provided with a panel assembly 270 thatselectively becomes transparent. Although the panel assembly may beconstituted by a single panel, the panel assembly is preferablyconstituted by a plurality of panels. The panel assembly 270 may beselectively changed into a see-through panel assembly, and, as such, auser can see the internal space behind the door through the panelassembly 270.

When the main door 100 and the sub door 200 are integrally formed into asingle door, unlike the construction shown in the drawings, a user cansee the main storage compartment through the panel assembly 270. In thiscase, the main door 100 may be just the cabinet 10, and the sub door 200may be considered the door for opening and closing the storagecompartment. In other words, the opening formed in the main door 100 maybe considered to be an opening formed in the cabinet 10.

As shown in FIG. 1, the sub door 200 may be provided with agroove-shaped handle 240 formed at the left side of the panel assembly270. The handle 240 may be vertically elongated and may be the samelength as the panel assembly 270. The sub door 200 may, of course, bethe left sub door provided at the left side of the cabinet 10. In thiscase, the handle 240 may be positioned at the opposite side.

The sub door 200 may be rotated in the same direction as the main door100. Specifically, the main door 100 and the sub door 200 may be rotatedabout a vertical rotating shaft, as shown in FIG. 2. However, the subdoor 200 may be configured to be rotated about a horizontal rotatingshaft like a home-bar.

Generally, the cabinet of the refrigerator is provided at the frontsurface thereof with a door switch (not shown) for detecting opening inthe door, and the storage compartment is provided therein with alighting device (not shown) for illuminating the interior of the storagecompartment when the door is opened.

According to the embodiment of the present invention, the door ispreferably changed into a see-through door by activation of the lightingdevice. Specifically, the door is preferably changed into a see-throughdoor by the lighting device provided in the main storage compartmentand/or the sub storage compartment such that the interior of the storagecompartment becomes visible from the outside.

More specifically, it is preferable that the interior of the storagecompartment become invisible upon deactivation of the lighting deviceand become visible upon activation of the lighting device. The interiorof a room is not made clearly visible through a window glass by a brightoutside. However, when the interior of the room is illuminated with abright light, the interior of the room is clearly visible through thewindow glass. The see-through door utilizes this principle. Theconversion of the see-through door is preferably performed by input of auser's command. Specifically, the door is preferably changed into asee-through door when a specific command is input to the refrigerator bya user.

The control process and control architecture associated with theconversion of the see-through door will be described later.

The specific construction of the sub door 200 is described withreference to FIGS. 3 and 4. As described above, the sub door 200 may besimply the main door for opening and closing the storage compartment. Asshown in FIG. 1, if the sub door is hingedly coupled to the main door orthe cabinet, the sub door 200 may be superimposed on the main door 100.In other words, the entire area of the sub door 200 may overlap theentire area of the main door 100. At this point, the entire area of themain door 100 is covered by the entire area of the sub door 200.Accordingly, since the main door 100 is shielded by the sub door 200,the sub door 200 defines the appearance of the front face of therefrigerator.

The sub door 200 includes a door frame 205 having a central opening 211.The door frame 205 constitutes the peripheral portion or the marginalportion of the sub door 200. In other words, the door frame 205constitutes upper and lower marginal portions and both lateral sidemarginal portions of the sub door 200.

Specifically, the door frame 205 may include an outer door 210constituting the marginal portion of the front face of the door and adoor liner 280 constituting the marginal portion of the rear face of thedoor. The outer door 210 and the door liner 280 may also be providedwith respective openings corresponding to the opening 211.

The door frame 205 may include cap decorations 260, which arerespectively coupled to the upper ends and lower ends of the outer door210 and the door liner 280. The outer door 210, the door liner 280 andthe cap decorations 260 may constitute a door having a predeterminedthickness and an internal space.

In conventional refrigerators, the internal space defined between theouter door 210, the door liner 280 and the cap decorations 260 istypically filled with foamed material for thermal insulation. The dooraccording to the embodiment, particularly the sub door 200, preferablyfurther includes the panel assembly 270 in addition to the door frame205. Preferably, further provided is a panel assembly 270 adapted to beconverted into a see-through door. As described hereinafter, the panelassembly 270 is preferably constructed to have a thermal insulationfunction.

The panel assembly 270 is preferably provided at the central portion ofthe sub door 200. Particularly, the panel assembly 270 is preferablyconfigured to correspond to the opening in the door frame 205.

In order to mount the panel assembly 270, the door frame 205 may furtherinclude an inner frame 230 interposed between the outer door 210 and thedoor liner 280. The inner frame 230 may also be provided at the centerarea thereof with an opening corresponding to the opening 211 in thedoor frame 205.

The door frame 205 may further include a door decoration 220. The doordecoration 220 may be mounted on the peripheral area of the opening inthe door frame 205 so as to substantially define the opening 211 in thedoor frame 205.

The sub door 200 may further include an upper hinge bracket 254 and alower hinge bracket 256 in addition to the panel assembly 270 so as tomake the sub door 200 rotatable. The sub door 200 may include a handle240, which enables a user to open and close the sub door 20X) whilegrasping the sub door 200. The sub door 200 may further include asupport 250.

Hereinafter, the process of assembling the sub door 200 will bedescribed with reference to FIG. 4.

The outer door 210 is first assembled with the door decoration 220, andthe handle 240 is then coupled to the assembly. A handle support 245 maybe interposed between the handle 240 and the outer door 210 or the doordecoration 220. The handle support 245 may be constituted by a metal rodso as to reinforce the rigidity of the handle 240. The door decoration220 may be coupled to the rear surface of the outer door 210. In theembodiment, the handle 240 may be coupled to the left end of the outerdoor 210 when viewed in FIG. 4.

Subsequently, the inner frame 230 is assembled with the rear surface ofthe outer door 210, and the supports 250 are assembled with the hingebrackets 254 and 256.

The supports 250 are provided at upper and lower ends of the panelassembly 270, and the supports 250 may be provided to correspond to thefour corners of the opening 211. The supports 250 are provided tocorrespond to the four corners of the panel assembly 270 so as toprotect the panel assembly 270. In other words, the supports 250 supportthe panel assembly 270 such that the weight of the panel assembly 270 isuniformly distributed to the door frame 205.

The supports 250 are assembled with the hinge brackets 254 and 256.Accordingly, the supports 250 further serve to reinforce the strength ofthe hinge regions.

Thereafter, the cap decorations 260 are coupled to the outer door 210from the rear. The cap decorations 260 may be coupled to the outer door210 by being respectively fitted on the upper and lower ends of theouter door 210.

Subsequently, the panel assembly 270 may be coupled to the outer door210 from the rear, and the door liner 280 may be coupled to the outerdoor 210 from the rear. Specifically, the door liner 280 may be securelycoupled to the outer door 210 by means of screws.

Finally, a gasket 290 is mounted on the rear surface of the door liner280, thus completing the assembly of the sub door 200.

The upper hinge bracket 254 and the lower hinge bracket 256 may beprovided with respective sub door hinges 130 coupled thereto. When thesub door 200 is closed with respect to the main door 100, the gasket 290serves to seal the clearance therebetween, thus preventing the leakageof cold air through the clearance.

As shown in FIG. 3, the panel assembly 270 may include a front panel271, which is exposed from the front surface of the sub door 200. Thefront panel 271 may be made of a transparent material, and its rearsurface may have a metal vapor-deposited thereon. The deposited metallayer may function to make the front panel 271 opaque when light is nottransmitted therethrough and make the front panel 271 transparent whenlight is transmitted therethrough.

Of course, the front panel 271 may include a color coating film, or maybe constituted by a color panel. Specifically, although the front panel271 is opaque under low-intensity light conditions, the front panel 271may become transparent under relatively high-intensity light conditions.

This means that the front panel 271 is opaque when the lighting devicebehind the front panel 271 is deactivated, and is converted into atransparent panel, that is, a see-through door, when the lighting deviceis activated. Accordingly, although the interior of the storagecompartment becomes invisible when the interior is dark, the interior ofthe storage compartment becomes visible through the front panel 271 whenthe interior is bright.

The panel assembly 270 may include a thermal insulation panel providedbehind the front panel 271. The thermal insulation panel may include aplurality of thermal insulation panels. FIG. 3 shows an example in whichtwo thermal insulation panels 273 and 276 are provided. A spacer rod 272may be disposed between the front panel 271 and the thermal insulationpanel 273.

The front panel 271, which is made of a transparent material, is mountedat the central opening in the sub door 200 so as to constitute the frontsurface of the sub door 200.

The internal space defined in the door frame 205 of the sub door 200excluding the panel assembly 270 is preferably filled with a thermalinsulation material. Specifically, the space between the outer door 210and the door liner 280, that is, the space 285 provided at the marginalportion of the sub door 200, may be filled with a thermal insulationmaterial so as to prevent cold air from leaking between the gasket 290and the panel assembly 270.

Accordingly, the marginal portion of the sub door 200 is thermallyinsulated by the thermal insulation material, for example, polyurethane,and the central portion of the sub door 200 is thermally insulated bythe thermal insulation panels 273 and 276.

The space 285 is filled with the foamed material after the sub door 200is completely assembled, thus implementing secure coupling between theouter door 210 and the door liner 280.

The structure and the process of fabricating the panel assembly 270 willbe described in detail later.

FIGS. 5 to 8 are views showing a refrigerator according to a secondembodiment of the present invention.

As shown in FIGS. 5 and 6, a right refrigerating compartment door 25 ofthe refrigerator according to the second embodiment includes a main door300, which is hingedly coupled to the cabinet 11 and has therein acentral opening, and a sub door 400, fitted in the opening in the maindoor 300 and hingedly coupled thereto.

In the refrigerator according to the first embodiment, the main door andthe sub door are the same size when viewed from the front, and the subdoor overlaps the main door when the sub door is closed.

In contrast, in the refrigerator according to the second embodiment, thesub door 400 is configured to have a smaller size than that of the maindoor 300, and is fitted into the opening 310 in the main door 300 whenthe sub door 400 is closed.

Specifically, in the first embodiment, the sub door 200 is exposed tothe front of the main door 100 when the sub door 200 is closed withrespect to the main door 100. In the second embodiment, the sub door 400is fitted in the main door 3000 when the sub door 400 is closed withrespect to the main door 300. The former may be referred to as anoutside type sub door, and the latter may be referred to as an insidetype sub door.

Likewise in this embodiment, the main door 300 may simply be thecabinet. In this case, the sub door 300 may be considered to be a doorfor opening and closing the storage compartment 11.

As shown in FIG. 6, the main door 300 may be provided at the centerthereof with an opening 315, and may be provided at the rear surfacethereof with a sub storage compartment 311. In other words, the maindoor 300 may be provided with an opening 310 into which the sub door 400is fitted and the opening 315 for allowing access to the sub storagecompartment 311. A stepped portion is defined between the two openings310 and 315. In other words, the opening 315 for allowing access to thesub storage compartment 311 may be positioned inside the opening 310 inthe radial direction into which the sub door 400 is fitted.

When the sub door 400 is opened, it is possible to access the substorage compartment 311 through the opening 315 in the main door 300.That is to say, the sub storage compartment 311 may be accessed byopening only the sub door 400, without having to open the main door 300.

The sub storage compartment may be defined by a plurality of baskets(not shown) installed at different levels. Specifically, a cover (notshown) adapted to surround the plurality of baskets may be provided. Thecover may serve as a partition wall for isolating the sub storagecompartment and the main storage compartment from each other.Accordingly, the sub storage compartment may be positioned in front ofthe main storage compartment.

As shown in FIG. 6, a plurality of mounting protrusions 320 for mountinga plurality of baskets (not shown) may be provided at rear regions ofthe inner surfaces of the opening 315 in the main door 300. Theplurality of baskets may be two or three baskets, which are verticallyspaced apart from each other by predetermined distances. Accordingly, auser can access the sub storage compartment 311 by opening the sub door400 while leaving the main door 300 closed, as shown in FIG. 6.

Since the relationship between the main door and the sub door and therelationship between the main storage compartment and the sub storagecompartment are common in a DID refrigerator, descriptions thereof areomitted.

The sub door 400 is internally provided with a panel assembly 470 thatselectively becomes transparent. Although the panel assembly may beconstituted by a single panel, the panel assembly is preferablyconstituted by a plurality of panels as described hereinafter. The panelassembly 470 may be selectively changed into a see-through panelassembly, and as such, a user can see the internal space behind the doorthrough the panel assembly 470.

More specifically, the sub storage compartment 311 is visible throughthe panel assembly provided at the opening 411 of the sub door 400 andthe opening 315 provided in the main door 300. It is possible to see theinterior of the sub storage compartment 311 even in the state in whichthe sub door 400 is closed, and it is possible to easily perceive wherea specific object is positioned in the sub storage compartment 311.Thereafter, a user can easily take a desired object out of the substorage compartment 311 by opening the sub door 400.

For example, assuming that 12 similar objects are stored in the substorage compartment 311 in a 4×4 matrix, a somewhat long period of timemay be required to open the sub door 400, find a desired specific objectamong the 12 similar objects and take the desired object out of the substorage compartment 311. However, in the case where the 12 similarobjects are visible from the outside, there is no need to take time tofind and select the specific object. Specifically, since a user hasalready seen the position of the specific object, the user can quicklytake out the specific object after merely opening the sub door 400.Therefore, it is possible to minimize the loss of cold air and toimprove the user's convenience.

Hereinafter, the structure of the sub door 400 will be described indetail with reference to FIGS. 7 and 8.

The sub door 400 according to this embodiment includes a door frame 405having a central opening 411.

The door frame 405 may include an inner frame 410 constituting themarginal region of the rear side of the sub door 400, and a door liner480, coupled to the inner frame 410 to constitute the marginal region ofthe rear surface of the sub door 400.

Unlike the first embodiment, the inner frame 410 and the door liner 480may be integrally formed with portions corresponding to cap decorationsprovided at the upper and lower ends thereof without providing separatecap decorations.

Supports 450 may be respectively disposed between upper ends of theinner frame 410 and the door liner 480 and between the lower ends of theinner frame 410 and the door liner 480.

An upper hinge bracket 454 and a lower hinge bracket 456 may berespectively coupled to one side of the upper support 450 and one sideof the lower support 450. Sub door hinges may be respectively coupled tothe upper hinge bracket 454 and the lower hinge bracket 456.

Unlike the construction shown in the drawings, the cap decorations maybe respectively coupled to upper ends and lower ends of the inner frame410 and the door liner 480, and upper and lower hinges (not shown) maybe directly coupled to the cap decorations.

The door liner 480 may be provided at the rear surface thereof with agroove in which a gasket 490 is fitted. When the sub door 400 is closedwith respect to the main door 300, the gasket 490 serves to seal theclearance between the sub door 400 and the main door 300, thuspreventing the leakage of cold air. Specifically, the gasket 490 may bedisposed at the position between the two openings 310 and 315.

As shown in FIGS. 7 and 8, the panel assembly 470 of the sub door 400according to the second embodiment is coupled to the front surface ofthe sub door 400. Specifically, the panel assembly 470 may be coupled tothe inner frame 410 from the front.

The panel assembly 470 may be identical or similar to the panel assemblyof the first embodiment. However, the front panel 471 of the panelassembly 470 according to this embodiment is distinguished from thefirst embodiment in that the front panel 471 is not covered at themarginal area thereof with the outer door 210 but is coupled to thefront surface of the inner frame 410 having the opening.

In the first embodiment, the marginal region of the front surface of thesub door 200 is constituted by the outer door 210 and the central regionof the front surface of the sub door 200 is constituted by the frontpanel 271. According to the second embodiment, the front surface of thesub door 400 is preferably constituted by the front panel 471. In otherwords, the marginal region and the central region of the front surfaceof the sub door 400 are preferably constituted by the front panel 271.

To this end, the front panel 471 is preferably configured to be largerthan the plurality of thermal insulation panels 473 and 476. That is,the front panel 471 preferably not only covers the entire area of thethermal insulation panels but also extends outward beyond the boundaryof the entire area.

The plurality of thermal insulation panels 473 and 476 may be fitted onthe inner surface of the opening in the inner frame 410, that is, on theinner surface of the opening 411, and the rear surface of the secondthermal insulation panel 476 may be supported by the door liner 480.

A rectangular spacer rod 472 may be interposed between the front panel471 and the first thermal insulation panel 473 so as to maintain apredetermined spacing therebetween.

A handle may be coupled to the left side of the inner frame 410 and thedoor liner 480, which are coupled to each other.

For the purpose of coupling between the inner frame 410 and the handle440, the left side surface of the inner frame 410 may be provided with apair of catch ribs 412, which engage with a pair of fitting ribs 442vertically formed on the right side surface of the handle 440.

The pair of catch ribs 412 may be configured in such a manner as tolaterally project from the left side surface of the inner frame 410 andthen be respectively bent forward and rearward.

In order to match the catch ribs 412, the pair of fitting ribs 442 maybe configured to be laterally projected from the right side surface ofthe handle 440 and then be respectively bent forward and rearward.

As a consequence of coupling between the inner frame 410 and the doorliner 480, a predetermined space 485 is defined in the marginal portionof the sub door 400. The space 485 may also be defined by coupling thecap decorations to the inner frame 41 and the door liner 480. In otherwords, the space 485 is defined in the upper and lower marginal portionsand both lateral side portions of the sub door 400. The space may bereferred to as a filling space that is filled with a thermal insulationmaterial.

Accordingly, the marginal portion of the sub door 400 may be thermallyinsulated by the thermal insulation material, and the central portion ofthe sub door 400 may be thermally insulated by the panel assembly 470.

The region of the front panel 471 that is positioned outside the thermalinsulation panel in the radial direction may be in close contact withthe inner frame 410. The region of the front panel 471 may also be inclose contact with the cap decorations. The latter is the case where theupper and lower portions of the inner frame are constituted by separatecap decorations.

After the handle 440 is coupled to the inner frame 410, the capdecorations may be coupled to the inner frame 410 if necessary.Subsequently, the panel assembly 470 may come into close contact withthe inner frame 410 from the front. At this point, the inner frame 410and the panel assembly 470 may be temporarily coupled to each other bydisposing a piece of transparent adhesive tape or a transparent adhesivetherebetween. Specifically, the transparent adhesive tape may bedisposed between the inner frame 410 and the rear surface of themarginal region of the front panel 471 (i.e. the marginal regionpositioned outside the thermal insulation panel in the radialdirection).

After the panel assembly 470 is temporarily coupled to the inner frame410, the door liner 480 may be coupled to the inner frame 410 from therear position of the inner frame 410. Thereafter, the space 485 isfilled with a foamed material, with the result that the panel assembly470 is closely coupled to the door frame 405.

Hereinafter, the structure and the process of fabricating the panelassembly will be described with reference to FIG. 9.

FIG. 9 is a schematic view of the panel assembly 270 according to thefirst embodiment of the present invention. The panel assembly 270 may besubstantially identical to the panel assembly 470 according to thesecond embodiment except that the front panel 271 is the same size asthe thermal insulation panels 273 and 276.

The front panel 271 is preferably made of thermally hardened glass thatis enhanced in strength by being heated to about 600 to 700° C.

In the thermal hardening process, the glass may be heated above theglass-transition temperature (Tg) and may then be rapidly cooled so asto create compression stress due to the difference in shrinkage betweenthe inner portion and the outer portion of the glass.

The depth of the compression stress in the thermal hardening process isabout 20% of the overall thickness of the glass.

The rear surface of the front panel 271 may be vapor-deposited withmetal, such as titanium or nickel, so as to create a deposited layer2712. When the lighting device in the storage compartment is activated,the deposited layer 2712 may allow the light emitted from the lightingdevice to be transmitted to the outside through the front panel 271,thus making the interior of the storage compartment visible. Meanwhile,when the lighting device is deactivated, the deposited layer shields theinterior of the storage compartment, thus making the interior of thestorage compartment invisible. Of course, the front panel 271 may bemade of glass, or may be provided thereon with a color coating layer.

Accordingly, it is preferable that the front panel 271 be converted intoa see-through panel when light is transmitted therethrough and beconverted into an opaque panel when light is not transmittedtherethrough. It is further preferable that the front panel 271 enablelight to be elegantly transmitted therethrough, unlike general windowglass. Thanks to this effect, the atmosphere of the room in which therefrigerator is positioned may be made more elegant.

The first thermal insulation panel 273 and the second thermal insulationpanel 276 are preferably made of chemically strengthened glass that wasproduced by soaking the glass in electrolyte solution at the glasstransition temperature or higher.

In the chemical strengthening process, when glass in an electrolytesolution containing molten salt, such as KNO₃, is heated to atemperature below the glass transition temperature, some of the sodiumions on the glass are replaced with potassium ions, thus creatingcompression stress caused by the difference between the ionic radii.

In the chemical strengthening process, the depth of compression stressmay be about 2 to 3% of the overall thickness of the glass.

The rear surface of the first thermal insulation panel 273 may beprovided with a low-emissivity coating layer 2732 for reducing radiativeheat transfer to the inside of the storage compartment.

Glass equipped with such a low-emissivity coating layer 2732 is referredto as a low-e glass. The low-emissivity coating layer 2732 is typicallycreated by depositing the surface of glass with silver or the likethrough sputtering.

A vacuum space may be defined between the first thermal insulation panel273 and the second thermal insulation panel 276. To this end, the firstthermal insulation panel 273 includes a hole 2735 through which vacuumpumping is executed.

The hole 2735 is plugged with a plug 2736. The plug 2736 is insertedinto the hole 2735 so as to plug the hole 2735 after completion of thevacuum pumping.

The process of coupling the first thermal insulation panel 273 and thesecond thermal insulation panel 276 and forming the vacuum spacetherebetween will now be described.

Frit glass 275 is first dispensed onto the marginal area of the secondthermal insulation panel 276. Frit glass 275 is a glass raw materialcomposed of glass powder having a melting point of about 400-500° C., abinder, and the like. The frit glass 275 has a melting point lower thanthe first and second thermal insulation panels 273 and 276.

After the frit glass 275 is arranged along the marginal area of thefront surface of the second thermal insulation panel 276, the firstthermal insulation panel 273 is placed thereon. Thereafter, the fritglass 275 is melted and then solidified, thus coupling the first andsecond thermal insulation panels to each other.

Prior to placing the first thermal insulation panel 273 after the fritglass 275 is arranged, a plurality of spacers 274 are arranged on thesecond thermal insulation panel 276.

Since there is a limit to which the thickness and strength of thethermal insulation panel, which is made of glass, can be increased, theplurality of spacers 274 serves to support the center area of thethermal insulation panel so as to prevent the center area from drooping.

The spacers 274 may be made of stainless steel, glass, plastic, or thelike. The spacers 274 are preferably made of a material capable ofsupporting the first thermal insulation panel 273 and the second thermalinsulation panel 276 in the state of maintaining a predetermined spacingtherebetween and of almost completely eliminating conductive heattransfer.

After the first thermal insulation panel 273 is coupled to the secondthermal insulation panel 276, vacuum pumping is executed through thehole 2735 to create a vacuum between the first thermal insulation panel273 and the second thermal insulation panel 276.

After the vacuum pumping, the hole 2735 is plugged with the plug 2736.The plug 2737 may be covered by frit glass 2737. In this case, the plug2736 may not protrude from the surface of the first thermal insulationpanel 273, and the frit glass 2737 may be slightly convex from thesurface of the first thermal insulation panel 273.

The frit glass 2737 may have a lower melting point than the frit glass275 disposed between the first and second thermal insulation panels 273and 276.

After the operation of coupling the first and second thermal insulationpanels 273 and 276 to each other and of performing the vacuum pumpingand the sealing is completed, the rectangular spacer rod 272 having apredetermined thickness is placed on the front surface of the firstthermal insulation panel 273, and the front panel 271 is attachedthereto.

The spacer rod 272, the first thermal insulation panel 273 and the frontpanel 271 are attached to each other by means of a transparent adhesiveapplied therebetween.

As shown in FIG. 4, the panel assembly 270, which has been prepared inthis way, is disposed between the outer door 210 and the door liner 280,and the outer door 210 and the door liner 280 are coupled to each other,thus completing fabrication of the sub door 200.

In the second embodiment, the panel assembly 370 may be attached to thefront surface of the inner frame 410 using a transparent adhesive. Atthis point, the first and second thermal insulation panels 473 and 476are disposed in the opening in the inner frame 410, and the marginalarea of the front panel 471 is attached to the front surface of theinner frame 410.

The thermal insulation panel is composed of a plurality of glass panels,which are provided therebetween with the space for hindering heattransfer therebetween. Furthermore, since the glass panels are made oflow-emissivity coating glass, it is possible to minimize heattransmitted through the panel assembly 470.

FIG. 10 is a graph illustrating the variation in temperature of twothermal insulation panels when a vacuum insulation space is createdbetween the two thermal insulation panels using vacuum-pumpingtechnology. FIG. 11 is a graph illustrating the variation in temperatureof two thermal insulation panels when a vacuum insulation space iscreated between the two thermal insulation panels using vacuum-chambertechnology.

In the vacuum-pumping technology shown in FIG. 10, when the frit glass275 is heated for welding in a heating apparatus, the frit glass 275 maybe heated to about 470° C.

The welding operation is indicated by character “A” in FIG. 10. In thewelding operation, the frit glass 275 is heated to about 470° C. fromthe ambient temperature, i.e. 20° C., for about 90 minutes. The heatingtemperature is set to be the melting point of the frit glass 275 orhigher, and may be heated to a temperature range of 300-400° C.depending on the kind of frit glass.

The welding operation is maintained at about 470° C. for about 30minutes, and the temperature is then lowered to about 370° C. for about30 minutes.

The operation of creating the vacuum and sealing, which is indicated bycharacter “B”, may be performed at about 370° C.

The operation of creating the vacuum and sealing may be performed forabout 5 hours with maintenance of the temperature is maintained at about370° C.

The operation of creating the vacuum and sealing is performed in such away as to connect a pipe of a vacuum-pumping device to the hole 2735 soas to execute vacuum pumping, plug the hole 2735 with the plug 2736, andseal the hole by welding the frit glass 2737.

The temperature of 370° C. is determined in consideration of the meltingpoint of the frit glass 2737, and the operation of creating the vacuumand sealing may be carried out at a temperature range of 300-400° C.depending on the kind of frit glass 2737.

The pipe of the vacuum-pumping device may be cut after vacuum pumpingsuch that the end portion of the pipe fitted in the hole 2735 serves asthe plug 2736.

Subsequently, the spacer rod 272 is placed on the front surface of thefirst thermal insulation panel 273, and the front panel 271 is attachedto the spacer rod 272 using a transparent adhesive.

The outer circumferential surfaces of the first thermal insulation panel273, the frit glass 275, the second thermal insulation panel 276, thespacer rod 272 and the front panel 271 may be sealed using a sealant.

Thereafter, in the operation indicated by character “C” in FIG. 10, thecomponents may be cooled to 60° C. from 370° C. in about 2 hours, thuscompleting fabrication of the panel assembly 270.

Meanwhile, the vacuum chamber technology illustrated in FIG. 11, whichis configured to fabricate the panel assembly in a vacuum chamber,includes (1) a vacuum heating operation, (2) a vacuum welding operation,(3) a first cooling operation. (4) a capping operation, and (5) a secondcooling operation.

In the vacuum heating operation (1), the frit glass 275 is dispensed tothe marginal area of the first thermal insulation panel 273 disposed ina vacuum chamber, and the plurality of spacers 274 are arranged thereon.The second thermal insulation panel 276 is placed thereon. The air inthe vacuum chamber is removed to create a vacuum in the chamber.Subsequently, the vacuum chamber is heated to about 420° C. in about 80minutes to raise the internal temperature in the vacuum chamber.

In the vacuum welding operation (2), the internal temperature in thevacuum chamber is maintained at about 420° C. for 40 minutes such thatthe frit glass 275 is melted so as to weld the second thermal insulationpanel 276 to the first thermal insulation panel 273.

In the first cooling operation (3), the resulting components are cooledto about 250° C. from about 420° C. in 1 hour.

In the capping operation (4), the hole 2735 is plugged with the plug2736, and the clearance between the hole 2735 and the plug 2736 iscompletely sealed with the frit glass 2737.

In the second cooling operation (5), the resulting components aregradually cooled to the ambient temperature from about 250° C. for about5 hours, thus completing the fabrication of the panel assembly 270.

A comparison between the two technologies for creating a vacuum will nowbe made below.

Although the vacuum-pumping technology is easily applied to the presentinvention because the technology has generally been used in creatingvacuums, the technology has a disadvantage of leaving a cut end of apipe after the creation of the vacuum. Hence, the hole must be formed ata position that is invisible from the outside of the sub door.

Since the panel assembly according to the embodiments of the presentinvention is made of transparent glass, it should be noted that the cutend must be invisible. Accordingly, the positioning of the hole isextremely restrictive, and it may be required to provide an additionalpart for shielding the hole.

In the vacuum chamber technology, since the work of assembling thecomponents is carried out in a vacuum chamber, the vacuum chamber mustbe sufficiently large to accommodate both the front panel and thethermal insulation panel.

Meanwhile, since the assembly work is carried out in the vacuum chamber,the cut pipe is not left in the hole after completion of the assembly,and the hole may be easily sealed. However, since the hole must be stillformed in the transparent thermal insulation panel, it may be requiredto provide an additional part for shielding the hole.

The vacuum space of the panel assembly 270 and 470 provides a remarkableeffect in terms of thermal insulation performance. However, the panelassembly may make fabrication difficult, and may make the design thereofunpleasant due to the presence of the hole. Accordingly, an inert gasspace, which is filled with argon or the like, may be provided in placeof the vacuum space. Inert gas has better thermal insulation performancethan air. For this reason, it is possible to provide space between thefront panel and the thermal insulation panel and between thermalinsulation panels, and to fill the spaces with inert gas so as to ensurethermal insulation performance.

As described above, the main door or the sub door according to theembodiments of the present invention may be selectively converted into asee-through door. Specifically, upon the input of specific command froma user, the main door or the sub door may be converted into asee-through door.

The conversion into a see-through door may be implemented by activatingthe lighting device 600 disposed in the storage compartment. Uponactivation of the lighting device 600 in the storage compartment, thestorage compartment becomes bright. Accordingly, the light in thestorage compartment is transmitted to the outside through the door,whereby the interior of the storage compartment becomes visible throughthe door from the outside.

The kind of user input for conversion into a see-through door may vary.Furthermore, the kind of sensor for detecting such user input may alsovary.

The refrigerator according to the embodiment of the present inventionmay include a sensor for detecting user input for the conversion to asee-through door.

Specifically, the sensor 500 is preferably a sensor for detecting soundwaves propagating through a medium. The user input may be detected byidentifying sound waves, detected by the sensor, as a certain pattern ofsound waves.

This indicates that the sensor 500 can detect the occurrence of avibration even when the position at which the sound waves are generatedis spaced apart from the position at which the sound waves are detected,as long as the medium is continuous. In other words, considering theentire surface area of the refrigerator door, this indicates that thedistance between the sound wave generation position and the sound wavedetecting position can be maximally increased as long as the continuityof the medium of the refrigerator door is maintained.

The sound wave generating position may be considered to be the positionat which the user input for conversion into a see-through door isapplied, and the sound wave detecting position may be considered to bethe position at which the user input is detected by the sensor.Therefore, by adoption of the sensor for detecting sound waves, theposition and manner in which the user input is applied may be variouslychanged regardless of what the posture a user assumes or whether a useris holding objects with both hands.

According to this embodiment, by virtue of the adoption of the soundwave sensor, a user can apply input to the front surface of the door atany position. Furthermore, the sensor may be located at any position onthe door without limitation. In this regard, considering thecharacteristics of sound waves, the same continuous medium is preferablyprovided between the position at which a specific vibration input isapplied and the position at which the vibration input is detected. Inother words, it is preferable that sound waves, which are generated byuser knock input applied at a certain position, be transmitted to apredetermined position through a consistent medium for detection.

The sensor 500 may include a microphone for measuring sound wavessubstantially transmitted through a medium. Although the medium of thefront panel is different from air, sound waves may be efficientlytransmitted to a point very far away because of the inherent property ofsound waves.

For example, when a person puts his/her ear to a train rail, the personcan perceive that there is a running train at a location very far away.This indicates that sound waves are efficiently transmitted a longdistance through the train rail, which serves as a medium.

Of course, vibrations of the medium itself rather than sound wavesgenerated by a user knock input may be generated.

However, vibrations of a medium are transmitted through the surface ofthe medium. That is, the vibrations may be referred to as transversewaves. Accordingly, as the distance between the input position and thedetection position in the same medium is increased, the damping width isincreased. In contrast, the damping width of sound waves is very small.Accordingly, considering the size of a refrigerator, it is consideredmore efficient to detect sound waves transmitted through the inside ofthe medium rather than vibrations transmitted through the surface of themedium.

The sensor for detecting sound waves is intended to detect thetransmission of sound waves through the front panel itself. Accordingly,it is possible to obviate the mounting of an additional device, such asa touch panel, to the front panel. This indicates that it is possible toeliminate disadvantages, such as increased cost and complexity anddecreased durability, attributable to the addition of a touch panel.Furthermore, this indicates that the knock input area can besubstantially extended over the entire area of the front panel.

As described above, the front panel according to this embodiment ispreferably constituted as a medium through which a sound wave caused byuser input is transmitted. In other words, it is preferable that userinput be applied to the front panel, which is exposed from the frontface of the door, and that the sound wave transmitted through the frontpanel be detected by the sensor. The sensor may include a sensor device,particularly a microphone, for detecting the transmission of sound wavesthrough a medium.

When a microphone is used as the sensor device, the sound wavestransmitted through the front panel are transmitted to the microphonethrough the air, which serves as another medium. Accordingly, it may becritical to shield the sound wave transmitting space, located betweenthe front panel and the microphone, from the outside. This is becauseexternal noise may be input to the microphone if the space is notshielded. Accordingly, it is critical to keep the microphone module,including the microphone, in close contact with the front panel and tomaintain such close contact, as will be described later. Furthermore, itis also critical to continuously apply a force to a support member forsupporting the microphone in the contact direction. That is, the supportmember may also be caused to closely contact the front panel.

Accordingly, the input position can be spaced apart from the detectingposition by virtue of transmission through the front panel even if noadditional touch panel is provided. Particularly, the damping of soundwaves transmitted through a medium is comparatively very small, wherebythe spacing distance can be more efficiently increased.

In the embodiments of the present invention, it is preferable that theknock input from a user be applied to the center area of the door, whichis convertible into a see-thorough area, and that the sensor fordetecting the user input be provided at the marginal area of the door,which is not convertible into a see-through area. Of course, the pointto which the knock input is applied and the point at which the vibrationis detected are preferably positioned on a single front panelconstituted by a continuous medium. Discontinuity of the medium meansthat variation in the detection value may be higher depending on theposition at which knock input is generated even when the same vibrationinput is applied. Hence, the detection accuracy is inevitably decreased.

Furthermore, this indicates that the danger of determining that inputapplied to a medium other than the front panel is a normal knock inputcan be reduced. In other words, this indicates that a malfunctionwhereby an impact applied not to the front panel but to another portionof a refrigerator, is recognized as normal knock input can be remarkablydecreased. This is because the cabinet of a refrigerator is typicallyconstituted by a medium different from that of the front panel.

For this reason, it is strongly preferable that the knock inputapplication point and the knock input detection point be positioned on asingle front panel as in the embodiments of the present invention.

The impact applied to other portions of the refrigerator may be thevibration of the refrigerator itself. Any portion of the refrigeratormay vibrate due to various causes, such as the vibrations caused bydriving of the refrigeration cycle or vibrations caused by externalforce applied to the refrigerator. At this time, the vibrations of therefrigerator may be transmitted through the front panel, thusinfluencing the sensor. In other words, when an intensive vibration isgenerated, the front panel itself inevitably vibrates, even if the twomedia are different from each other. Accordingly, there may be acircumstance whereby, when vibrations of the medium itself are detected,the vibrations of the refrigerator itself are falsely recognized asnormal knock input.

However, it is known that the damping width of sound waves throughdifferent, i.e. discontinuous, media is increased. Accordingly, soundwaves generated by an impact applied not to the front panel but toanother portion of the refrigerator may be sufficiently dampened whilebeing transmitted through the different media. Therefore, when the knockinput is recognized by detecting sound waves, the malfunctions caused byimpacts or vibrations applied to portions other than the front panel canbe remarkably reduced. Specifically, in the case where the microphonefor detecting sound waves is used, since the microphone is lesssensitive to the vibration of the refrigerator itself, errors wherebythe vibration of the refrigerator itself is recognized as normal knockinput can be remarkably reduced.

As shown in FIG. 12, the refrigerator according to this embodiment ofthe present invention may include the sensor 500 for detecting userinput for conversion into the see-through door, a main controller 700and the lighting device 600.

The sensor 500 may be provided on the front surface of the door, forexample, the front panel 271 or 471 of the sub door 200 or 400, so as todetect the knock input by a user. In other words, the sensor 500 may beprovided on the front panel so as to detect the knock input that isapplied thereto by a user.

When the normal input for conversion into a see-through door iscorrectly applied by a user, the main controller 700 activates thelighting device 600. As a result, the interior of the storagecompartment is brightened, whereby the door is converted into asee-through door.

Specifically, the sensor 500 may include a second device for detectinginput for conversion into the see-through door. In particular, thesensor 500 may include a microphone 510 as a sensor device for detectingsound waves. In other words, the sensor 500 preferably includes themicrophone 510, which is configured to detect sound waves transmittedthrough the inside of a medium rather than detecting the vibration ofthe medium itself.

The microphone 510 may detect not only sound waves caused by a user'sknock signal but also sound waves caused by external noise. The latterkind of sound wave or vibration may be referred to simply as “noise”.Accordingly, it is necessary to mechanically prevent such noise frombeing input to the microphone 510.

To this end, the microphone 510 is preferably in close contact with themedium. In particular, the microphone 510 is preferably in close contactwith the front panel 271 or 471. Accordingly, a mounting member orsupport member for causing the microphone 510 to closely contact thefront panel is required. The concrete embodiments of the member will bedescribed later.

The main controller 700 may be considered a main microcomputer adaptedto perform general control of a refrigerator, that is, a controller forcontrolling the driving of a compressor or various fans.

The refrigerator is typically provided with a door switch 800.Therefore, it is possible to determine whether or not the refrigeratordoor is opened based on the door switch 800. When the door is opened,the door switch 500 is switched to the ON state so as to activate thelighting device 600 in the storage compartment. When the door is closed,the door switch is switched to the OFF state, whereby the lightingdevice 600 in the storage compartment is deactivated. The ON state andOFF state of the door switch may be reversed with each other. Theoperation of the door switch 800 and the lighting device 600 may beimplemented independently from the controller 700. Of course, it willalso be possible for the controller 700 to determine whether the door isopen or closed by virtue of the door switch 800, to thus control thelighting device 600 depending on the determination.

In this embodiment, the process of controlling the door switch 800, themain controller 700 and the lighting device 600 may be performed in twoways. The lighting device 600 may include a main lighting device 610 anda sub lighting device 620.

An operational example in which the main door itself is converted into asee-through door is first described.

For the conversion into a see-through door, the main controller 700 mayoperate the lighting device 600, in particular, the main lighting device610. The conversion into a see-through door is preferably implementedunder the assumption that the main door is in a closed state.Accordingly, in response to the determination of input of the normalknock signal, the main controller 700 preferably controls the mainlighting device 610 to operate even if the door switch 800 is in an ONstate (the door is closed). The main controller 700 may control theoperation of the main lighting device 610 in accordance with thealgorithm for conversion into a see-through door as long as the door isnot opened. For example, the main controller 700 may control the mainlighting device such that the brightness of the lighting device isgradually increased. Furthermore, it is possible to control the mainlighting device such that the main lighting device stops after the mainlighting device has been operating for a predetermined period of time.In other words, it is possible to control the main lighting device sothat it turns off after a predetermined period of time has elapsed.

In the case where the door is opened while conversion into a see-throughdoor is maintained, the algorithm may be overridden by the normalcontrol algorithm for the main lighting device 610. In other words,control may be performed such that the main lighting device 610 isalways operated while the main door is opened. Of course, it may also becontrolled such that an alarm is generated and the main lighting device610 is turned off when the door has remained in an open state for anexcessively long period of time.

An operational example in which not the main door but the sub door isconverted into a see-through door will now be described. In thisexample, the sub lighting device 620 for making the interior of the substorage compartment bright is preferably provided, in addition to themain lighting device 610 for making the storage compartment bright.

Although not shown in the drawings, the sub lighting device 620 mayinclude an LED module mounted on one or both inner sides of the opening115 or 215 of the main door 100 to illuminate the sub storagecompartment. The LED module may be constituted by an elongated circuitboard and a plurality of LEDs arranged on the circuit board atpredetermined intervals.

The LED module is preferably mounted in a groove formed in both innersides of the opening in the main door 100 and is preferably covered by atransparent cover so as to protect the LED module and prevent the entryof moisture or pollutants.

In response to the determination of input of the normal knock signal,the main controller 700 may activate the sub lighting device 620 toconvert the sub door into a see-through door. At this time, the sublighting device 620 is preferably controlled to be operated for apredetermined period of time. If a predetermined time has not elapsedwhen the sub door is opened by a user, the sub lighting device 620 maybe controlled to be continuously activated.

If a predetermined time has not elapsed, a user cannot open the maindoor. In this case, there is no need to maintain the conversion of thesub door into a see-through door. Accordingly, when it is determinedthat the main door has been opened through the door switch while the subdoor is in the state of having been converted into a see-through door,the operation of the sub lighting device 620 is preferably controlled tobe stopped.

Consequently, unnecessary operation of the lighting device 600 may bereduced through control of the relationship between the main controller700, the lighting device 600 and the door switch 800.

The main controller 700 may determine whether a normal signal forconversion into a see-through door has been input, based on the signalinput through the sensor 500. Specifically, the main controller 700 maydirectly determine whether the input signal is a normal signal or noise.In this case, an overload may be applied to the main controller 700, andthe effect of noise inherent in the signal line itself may be furtherincreased owing to the distance between the sensor 500 and the maincontroller 700.

As described above, the sensor 500 is preferably provided on the frontpanel 271 or 471. In most cases, the main controller 700 is provided onthe cabinet 10 rather than the door. Hence, the distance between thesensor 500 and the main controller 700 is increased, which means thatthe length of the signal line is increased. This indicates that thenormal signal for conversion into a see-through door may be contaminatedby the noise inherent in the signal line and before being input to themain controller 700. Therefore, the recognition rate of the signal forconversion into a see-through door is inevitably deteriorated. Inparticular, in the case where the sensor includes a microphone as asensor device, it is common for the signal output through the microphoneto be on the order of mV whereas the signal input to the main controller700 must be on the order of V. Hence, it is undesirable for the maincontroller 700 to determine whether the signal is a normal signal forconversion into a see-through door because of the physical difference inmagnitude of the signals.

In particular, refrigerators are electronic appliances that consume highvoltage and high current. Accordingly, the amount of electrical noisesgenerated by refrigerators is relatively high. This means that thesignal on the order of mV, output through the microphone, is more easilyaffected by such electrical noise.

In order to solve this problem, according to this embodiment, the sensor500 for detecting input for conversion into a see-through door ispreferably modularized. In this regard, the modularized sensor may bereferred to as a sensor module.

The sensor module or knock sensor module, which is denoted by thenumeral “500”, may include the microphone 510, as the sensor device, anda modular microcomputer 540. As described above, the microphone 510 is asensor device for detecting a knock on signal, and the modularmicrocomputer 540 serves to determine whether the signal detected by themicrophone 510 is a knock on signal.

For example, the modular microcomputer 540 determines whether the inputsignal is a normal knock on signal. When the input signal is determinedto be a normal knock on signal, the modular microcomputer 540 may sendto the main controller 700 a signal indicating that normal knock oninput has been applied. When the input signal is determined not to be anormal knock on signal, the modular microcomputer 540 may not send thesignal. For example, when the input signal is determined to be a normalknock on signal by the modular microcomputer 540, the modularmicrocomputer 540 may send a signal of 5V to the main controller 700. Inthe other case, the modular microcomputer 540 may send a signal of 0V tothe main controller 700. The latter is considered to be the case whereno signal is sent to the main controller 700.

Since the main controller 700 receives a signal that indicates only thatnormal knock on signal has been input, the main controller 700 does notperform any additional determination. Consequently, it is possible tominimize the effect of noise inherent in the signal line between themain controller 700 and the modular microcomputer 540. In the same wayas above, the modular microcomputer 540 may determine whether a normalknock on signal has been input based on a signal which is input throughthe modularized microphone and which contains minimal noise.Accordingly, an accurate recognition rate may be realized.

The knock sensor module or sensor module 500 may include a filter 520.The filter 520 serves to eliminate noise from the signal received fromthe microphone 510. Specifically, the filter 520 may be a noise filter.The filtered signals are preferably amplified through an amplifier.Therefore, the sensor module 500 preferably further include an amplifier530 for amplifying the filtered signal and transmitting the amplifiedsignal to the modular microcomputer 540. Specifically, the amplifier 530may be an operational amplifier.

The sensor module 500 preferably includes the filter 520, the amplifier530 and the modular microcomputer 540 mounted on a single PCB, and themicrophone 510 preferably extends from the PCB by means of a signalline. The structure by which the microphone 510 is mounted or securedwill be described later.

Hereinafter, the microphone or microphone module as the sensor device isdescribed in detail with reference to FIG. 13.

As shown in FIG. 13, a microphone 511 is preferably embodied as themicrophone module 510. In other words, the microphone 511 for directlydetecting sound waves is preferably provided in the state of beingreceived in a receptor 512. Accordingly, the microphone 511 and themicrophone receptor 512 may be collectively referred to as themicrophone 510 or the microphone module 510.

The microphone 511 may be configured to have a circular plate having apredetermined thickness. The microphone 511 is received in themicrophone receptor 512, and the movement of the microphone 511 is thusrestricted by the internal structure of the microphone receptor 512. Inother words, the microphone 511 is preferably supported such that themicrophone 511 floats in the microphone receptor 512.

The microphone receptor 512 is preferably made of a rubber material.Basically, the microphone 511 is closely fitted in the microphonereceptor 512. The microphone receptor 512 may be provided at the top andbottom thereof with openings 514 and 515, each of which may have acircular shape.

One side of the microphone 511 is considered to function as a sound wavereceiver 511 a for receiving sound waves. The sound wave receiver 511 amay be oriented to face one of the openings in the microphone receptor511. For the convenience of illustration, the sound wave receiver 511 ais illustrated as facing the lower opening 514.

A signal line 516 is connected to the other side of the microphone 511.The signal line 516 may be connected to the PCB of the knock sensormodule through the opening 515, as described above.

A predetermined space is preferably defined between the lower opening514 and the sound wave receiver 511 a. The predetermined space ispreferably sealed. To this end, the predetermined space is preferablysealed by causing the lower opening 514 to closely contact the medium,i.e. the front panel 271 or 471.

The predetermined space 517 may also be isolated from the upper opening515 by the close contact between the microphone 511 and the microphonereceptor 512.

In order to prevent the hermetical space from being damaged by theimbalance, a protrusion 513 is preferably provided along the peripheryof the lower opening 514. Specifically, even if the distribution offorce that acts on the microphone receptor 512 to cause the microphonereceptor to closely contact the medium subsequently becomes imbalanced,the hermetical space is effectively maintained by the elasticdeformation of the protrusion 513.

Accordingly, one side of the hermetical space is closed by the medium.Consequently, the air in the hermetical space is vibrated by sound wavestransmitted through the inside of the medium, and sound waves generatedby the vibration may be input to the microphone 511.

By virtue of the hermetical sealing, it is possible to block or suppressthe infiltration of external noise or vibrations into the predeterminedspace. Therefore, the erroneous determination of knock on input ormalfunctions attributable to external noise may be remarkably reduced,and the recognition rate of knock on input may be improved. In otherwords, when a knock on input is applied, the accuracy of thedetermination of whether a knock on input was applied may be greatlyimproved.

Hereinafter, the structure for mounting the sensor for detecting inputfor conversion into a see-through door will be described in detail. Inparticular, the structure for mounting the sensor will be described indetail under the assumption that the sensor is embodied as themicrophone module 510 shown in FIG. 13. For the convenience ofillustration, the signal line 516 is not shown in FIG. 14.

An example of the structure for mounting the microphone module 510 isfirst described with reference to FIG. 14.

According to this embodiment, the front panel 271 may constitute thecentral area of the door or the sub door, and the door frame 205 mayconstitute the marginal area of the door or sub door.

Specifically, FIG. 14 illustrates a partially broken away perspectiveview and an enlarged view of the structure for mounting the microphonemodule 510 on the sub door. For the convenience of illustration, thedoor liner 280 is omitted in FIG. 14.

According to this embodiment, the microphone module 510 is preferablymounted on the front panel 271 in a close-contact manner.

As shown in the drawings, the marginal area of the front panel 271 iscovered by the door frame 205, in particular, the outer door 210. Themicrophone module 510 is disposed between the outer door 210 and thefront panel 271. The microphone module 510 is preferably in closecontact with the front panel 271.

Specifically, in order to mount the microphone module 510 to the frontpanel 271 in close-contact manner, a support member 550 is preferablyprovided. The support member 550 may be disposed between the outer door210 and the front panel 271. Furthermore, the support member 550 may bedisposed between the outer door 210 and the door decoration 220.

Accordingly, both the microphone module 510 and the support member 550may be positioned outside the opening 211 in the radial direction forthe conversion into a see-through door. Therefore, the microphone module510 and the support member 550 may not be visibly exposed to the frontof the door even upon conversion into a see-through door. In addition,since the microphone module 510 and the support member 550 are preventedfrom being visibly exposed to the outside through the see-through door,the design of the door becomes elegant and neat.

Specifically, the support member 550 preferably includes an elasticelement 555. The elastic element 555 is preferably configured to exertan elastic force in the direction of causing close contact of themicrophone module 510. Therefore, it is preferable that the supportmember 555 always be biased toward the microphone module 510.

The support member 550 may include a fulcrum 551, a first extension 552extending in one direction from the fulcrum 551, and a second extension554 extending in the opposite direction from the fulcrum 551. Thefulcrum 551 may be interposed between the outer door 210 and the doordecoration 220.

The first extension 552 may be provided with a holder 553. The holder553 may be positioned at the end of the first extension 552. The holder553 may be provided with the microphone module 510 held therein.

The elastic element 555 may be disposed between the second extension 554and the door decoration 220 so as to exert an elastic force on thesecond extension 554, thus biasing the second extension 554 forward. Theelastic force is converted into an elastic force that pushes the firstextension 553 rearward like a seesaw, which is in turn converted throughthe holder 553 into a force that causes the microphone module 510 toclosely contact the front panel 271. Consequently, the elastic forcefrom the elastic element is continuously applied to the microphonemodule 510 so as to cause the microphone module 510 to closely contactthe front panel 271.

If the sub door 200 is configured so as not to include the doordecoration 220 and the inner frame 230, the support member 550 will bedisposed between the outer door 210 and the door liner 280. Accordingly,the support member 550 may be positioned outside the opening in the doorframe 205 in the radial direction.

The elastic element 550 may be a coil spring. The second extension 554may be provided on the rear surface thereof with a protrusion 556 forsupporting the elastic element 555.

Specifically, the elastic element 555 may be compressed a predeterminedamount at the time of assembly so as to exert an elastic force thatpushes the second extension 554.

Since the elastic element 550 biases the second extension 554, the firstextension 552, which is positioned at the opposite side with respect tothe fulcrum 551, biasedly pushes the microphone module 510, whereby themicrophone module 510 is caused to closely contact the front panel 271.In other words, it is possible to continuously maintain the state inwhich the microphone module 510 is in close contact with the frontsurface of the front panel 271.

Therefore, the microphone module 510 can efficiently recognize that auser is tapping the front panel 271.

Hereinafter, another embodiment of the structure for mounting themicrophone module 510 will be described with reference to FIGS. 15 and16.

As in the above embodiment, the microphone module 510 is preferablymounted so as to closely contact the front panel. In addition, themicrophone module 510 is mounted on the door frame such that themicrophone module 510 does not interfere with the see-through door.

The structure for mounting the microphone module according to thisembodiment may be applied to the door shown in FIG. 6. In other words,this structure may be applied to the case where the front panel 471defines the entire appearance of the front surface of the door.

Specifically, this structure may be applied to a door in which thethermal insulation panel is fitted in the opening and the rear marginalarea of the front panel is in close contact with the door frame.

As described above, the door frame 405 may include the inner frame 410.The inner frame 410 may be integrally formed with cap decorations 460,or the cap decorations 460 may be respectively coupled to the upper andlower ends of the inner frame 410.

Referring to FIGS. 15 and 16, the structure in which the microphonemodule 510 is mounted by means of the cap decorations 460 is shown.

More specifically, the cap decoration 460 may be provided at the frontregion thereof with a through hole 461 through which the microphonemodule 510 passes. The microphone module 510 may closely contact thefront panel 471 through the through hole 461.

For the purpose of close contact of the microphone module 510, a supportmember 560 is provided. The cap decoration 460 may be preferablyprovided with a seat portion 462 in which the support member 560 isstably received.

The microphone module 510 is at least partially received in a holder561. Accordingly, it is possible to cause the microphone module 510 toclosely contact the front panel and to maintain that state by pushingout the holder 561 toward the front panel 471. Therefore, the supportmember 560 preferably includes an elastic element 562 for biasedlysupporting the holder 561 and exerting an elastic force to the holder561.

The holder 561 may be provided with a slit or slot 561 a through whichthe signal line 516 shown in FIG. 13 is led out. Specifically, themicrophone module 510 may be received in the holder 561, and the signalline 516, for transmitting the signal input to the microphone module 510to the outside, may extend to the outside from the holder 561 throughthe slit or slot 561 a.

When the holder itself is made of a flexible material, the signal line516 may be fitted in the slit or slot 561 a, and may thus be stablysupported thereby.

The support member 560 may include a holder receptor 563 for receivingthe holder 561. The elastic element 562 may be disposed between theholder 561 and the holder receptor 563. Therefore, the holder 561 isalways biased forward with respect to the holder receptor 563.

The holder receptor 563 may be seated in the seat portion 462 such thatthe holder receptor 563 is always pushed forward. Specifically, thesupport member 560 including the holder receptor 563 may be securelyseated in place in the seat portion 462, and, as such, a force forsupporting the support member 560 forward may be applied to the supportmember 560 by itself.

To this end, a cover may be provided so as to cover the seat portion462. The cover 465 may be a hinge cover 465 for covering the sub doorhinge 130 mounted on the cap decoration 460. In other words, because thehinge cover 465 is coupled to the cap decoration 460, the support member560 may be supported by the hinge cover 465 and may thus be pushedforward.

Specifically, the cover 465 may be coupled to the cap decoration 460 bymeans of hook elements 466. At this point, the cover 465 may be providedwith a protrusion or rib 467 so as to push the support member 560forward.

Accordingly, the protrusion or rib 467 may serve to push the wholesupport member 560 forward and to maintain the pushed state of thesupport member 560. In addition, the elastic element 562 biases theholder 561 forward. As a result, the microphone module 510 may bemaintained in the state of being in close contact with the front panel471. In this embodiment, the microphone module 510 may, of course, comeinto close contact with the rear surface of the front panel 471 throughthe through hole 461.

The shape of the through hole 461 is preferably configured to mate withthe shape of the holder 561. Consequently, since it is possible toprevent the holder 561 from being displaced in the through hole 461, thetight contact force of the microphone module 510 can be efficientlymaintained.

The PCB of the knock sensor module 500 may be mounted on the lowersurface of the cover 465. In other words, the cap decoration 460 may beprovided with a space required to mount the sub door hinge 130 and thePCB. The signal line of the sensor or sensor module 500 may extend tothe inside of the cabinet 10 or the main door through the through hole131 and may be connected to the main controller 700.

Although the sensor module 500 may be mounted at any position on themarginal area of the door or the sub door, the knock sensor module 500will be preferably mounted on the upper cap decoration in order tosatisfactorily dispose the signal line.

Hereinafter, a further embodiment of the structure for mounting themicrophone module 510 will be described with reference to FIGS. 17 to19.

As in the above embodiments, this embodiment also suggests the structurefor mounting the microphone module 510 using the door frame, inparticular, the cap decoration 460.

The cap decoration 460 may include a through hole 461 formed therein.The microphone module 510 may pass through the through hole 461 and mayclosely contact the rear surface of the front panel 471.

The microphone module 510 is received in the holder 561, which isconfigured to be identical or similar to that in the above embodiments.The holder 561 may constantly push the microphone module 510 toward thefront panel, thus constantly causing the microphone module 510 toclosely contact the front panel.

Since the holder 561 may also be made of a flexible material, the holder561 may be flexibly restored toward the front panel in the state ofbeing compressed.

To this end, a holder mount 463 may be provided in the rear of thethrough hole 461. The holder 561 may be pushed into and mounted in theholder mount 463 while containing the microphone module 510 therein. Atthis point, the through hole 461 may be configured to have a largerdimension than the holder 561 in the direction in which the holder ismounted. Specifically, when the holder 561 is pushed from the left sidetoward the right side to be mounted, as shown in FIG. 18, the throughhole 461 preferably has a horizontal width greater than the horizontalwidth of the holder 561. Of course, the through hole 461 is preferablyconfigured to have a vertical width corresponding to the vertical widthof the holder 561 such that the upper and lower surfaces of the holder561 are tightly fitted in the through hole 461.

Specifically, a predetermined space may be defined between the holdermount 463 and the through hole 461, and the holder 561 may be fitted inthe predetermined space 464. More specifically, the width of thepredetermined space in the forward and rearward direction is decreasedas the holder 561 is inserted into the predetermined space. In otherwords, when the holder 561 is fully inserted into the space, the holder561 is compressed forward and rearward. Accordingly, the holder 561tends to flexibly return to its original state, thus generating a forcethat pushes the microphone module 510 forward.

The holder 561, which has been inserted, may be held in position. Asdescribed above, the cover 465 may be a cover for covering the capdecoration 460, or may be a hinge cover for covering the sub door hinge130. The cover 465 may also be coupled to the cap decoration 460 bymeans of the hook elements 466.

The cover 465 may be provided on the lower surface thereof with aprotrusion or rib 467 that protrudes downward. When the cover 465 iscoupled to the cap decoration 460, the protrusion or rib 467 pushes theholder 561. In other words, the protrusion or rib 467 pushes the holder561 in the direction in which the holder 561 is inserted into thethrough hole 461.

Consequently, the holder 561 may always be maintained in the compressedstate in the holder mount 463, and may be securely held regardless ofvibrations or movement of the door. Therefore, the microphone module 510may closely contact the front panel 471, and the close contact state maybe continuously maintained.

FIG. 20 is a conceptual diagram illustrating the position on thesee-through door on which the microphone module is mounted and the areaon the see-through door to which a user knock input is applied. In thecase where the main door or the sub door is constructed to be convertedinto a see-through door, the door has the opening 411 for defining thesee-through door. In other words, the storage compartment or the substorage compartment becomes visible from the outside through the arearadially inside the opening.

In the front surface of the door, the area inside the opening and atleast part of the area outside the opening are defined by the frontpanel, as mentioned above. In the front surface of the outside typedoor, the area inside the opening and at least part of the area outsidethe opening are defined by the front panel, and the marginal area of thedoor is defined by the door frame, as mentioned above. In the insidetype door, the entire front surface of the door is defined by the frontpanel.

Accordingly, the area to which a user knock input is applied may bebasically the entire area defined by the front surface of the frontpanel. However, a user may unconsciously apply the knock input to thearea that is converted into a see-through door. The area that issubstantially converted into a see-through door is considered as thearea radially inside the opening 211 or 411. Therefore, the entirerectangular area defined by the opening 211 or 411 may be defined as thearea on which a user applies the knock input.

Since this knock input area is a see-through area, the microphone moduleis preferably mounted on an area other than the see-through area. Ofcourse, the microphone module mounting area may be considered as anextension of the area of the front panel.

Accordingly, the mounting point of the microphone module is preferablypositioned at the area radially outside the opening 211 or 411. As shownin FIG. 20, the microphone module is preferably mounted at apredetermined area S surrounding the opening 211 or 411.

Since the predetermined area S is not the see-through area a user cannoteasily see the microphone module from the front of the door even thoughthe microphone module is in close contact with the front panel.Accordingly, the area to which the knock input can be applied may beefficiently expanded, and the distance between the knock input area andthe microphone module mounting area can be sufficiently increased.

In order to sufficiently prevent the microphone module from beingvisibly exposed from the front surface of the door, the rear surface ofthe predetermined area S may be provided with a printed layer. In otherwords, the area of the rear surface of the front panel according to thepredetermined area S may be formed with a printed layer. However, sincethe outside type door is constructed such that the predetermined area Sis covered by the door frame or the outer door, the printed layer may beomitted.

As described above, the user input for conversion into a see-throughdoor may be tapping on the front surface of the door, and the tappingmay be detected by the sensor device, in particular, the microphone.

So many environmental factors that apply vibrations to the front surfaceof the door may be present. The front surface of the door may bevibrated by impacts caused by opening and closing of the door, intensiveexternal noise, or the like. The input caused by these environmentalfactors may be determined to be a normal knock signal.

Accordingly, the sensor module enables a number of taps on the frontsurface of the door by a user to be determined as normal knock input.Specifically, the action whereby a user taps on the front surface of thedoor multiple times at a predetermined time intervals may be determinedas normal knock input.

By way of example, the action whereby a user taps on the front surfaceof the door twice within a predetermined period of time may bedetermined as normal knock input. Considering a user's general knockpattern, it will be appreciated that the interval between the firstknock and the second knock is about 600 ms or less. Since one second is1000 ms, the action whereby the first knock and the second knock occurat an interval shorter than 1 second may be determined to be normalknock input.

Accordingly, it is possible to remarkably prevent abnormal input frombeing determined as a normal knock signal by setting the time interval.

The intensities of users' knocks may be different from each other.Although the difference between the intensities of users' knocks may begreat, it will be appreciated that the difference between users'vibration patterns is very small. Accordingly, the difference betweenintensities of users' knocks may be compensated for by an algorithm, andnormal knock input may be efficiently recognized based on the pattern ofknock input and the time interval between knocks.

In other words, this indicates that the error whereby abnormal knockinput is recognized as normal knock input may be remarkably reduced.

As described above, when the knock input is determined to be normalknock input, the controller 700 activates the lighting device 600. Thecontroller 700 may control the lighting device to be turned off afterthe lapse of a predetermined period of time. When a user applies asecond knock input before the predetermined period of time has elapsed,the controller 700 may control the lighting device 600 to be turned off.The knock input in this case may be the same as the knock on input. Atthis point, in order to distinguish such knock input from knock oninput, only a single knock may be recognized as the knock off input.

It is, of course, preferable that the single knock input be recognizedas the knock off input only when the single knock input occurs beforethe lapse of a predetermined period of time after the determination ofknock on input

As described above, the substantially entire front surface of the doormay be used as the knock on input area by employing a sensor device suchas the microphone. In other words, a wide area may be used as the knockon input area without having to provide the knock on input area with anadditional sensor, such as a touch sensor or an electrostatic sensor.This means that it is possible to prevent an increase in costsattributable to the provision of a touch sensor, or an electrostaticsensor, or an additional panel including the sensor, and to improvedurability. Furthermore, the door can be simply constructed.

In addition, this indicates that the knock on input can be easilyapplied to a wide area regardless of a user's posture or even if bothhand are not free. Furthermore, the knock on input area may be definedto be substantially identical to the see-through area. Accordingly, itis possible to obviate elements that obstruct the transmission of lightthrough the see-through area, that is, components such as a touch panel.As a result, a clearer see-through may be realized.

There may be the case where two continuous knock on inputs are applied,for example inadvertently or due to children playing. While twocontinuous knock inputs within 600 ms of each other are determined to benormal knock input, there is a need to efficiently handle the case ofthree or more continuous knock inputs.

FIG. 21 illustrates an example of the control method at the time of thecontinuous generation of knock signals.

When a second knock signal is generated within 600 ms after generationof the first knock signal, the knock input is recognized as normal knockinput, thus activating the lighting device. The lighting device may bebasically controlled in such a manner as to be turned on, for example,for 10 seconds at the time of application of the normal knock input.

When the normal knock input is recognized by the application of thesecond knock signal, the second knock signal may be recognized as asubsequent first knock signal. Accordingly, when a third knock signal isfurther applied within 600 ms, the second knock signal and the thirdknock signal may be recognized as normal knock input. Therefore, thelighting device may be controlled to be further turned on for 10 secondsafter recognition of the third knock signal. In other words, when thenormal knock signals are continuously recognized, the ON state of thelighting device may be controlled to be continuously extended.

Accordingly, according to this embodiment, since the two normal knockinputs are recognized as the normal knock input signal, the reliabilityof knock input may be ensured. However, when two continuous normal knockinputs are applied due to a user playing, there may be the possibilitythat the lighting device is unnecessarily activated.

FIG. 22 illustrates another example of the control method at the time ofthe continuous generation of knock signals.

When the second knock signal is generated within 600 ms after generationof the first knock signal, the knock input is recognized as normal knockinput, thus activating the lighting device. The lighting device may bebasically controlled in such a manner as to be turned on, for example,for 10 seconds at the time of application of the normal knock input.

When the normal knock input is recognized by the second knock signal,the time interval between the second knock signal and the third knocksignal is determined. For example, when the third knock signal isapplied after a time interval of 600 ms, this may be recognized as anormal knock off signal. In other words, when the third knock signal isapplied after a time interval of 600 ms since the lighting device wasturned on by the second knock signal, this may be recognized as normalknock off input. However, when a third knock signal is applied within atime interval of 600 ms, the third knock signal may be ignored.

When the third knock signal is applied within the time interval of 600ms and the fourth knock signal is further applied within the timeinterval of 600 ms, the fourth knock signal may be recognized as knockoff input. Accordingly, the lighting device may be controlled to beturned off when the fourth knock signal is recognized. When the fifthknock signal is applied within a time interval of 600 ms after theapplication of the fourth knock signal, the fifth knock signal and thesixth knock signal may be recognized as normal knock on input, thusactivating the lighting device again.

Accordingly, according to this embodiment, when the normal knock inputsare repeatedly applied, the lighting device may be controlled to berepeatedly turned on and off. Thanks to this control method, it ispossible to reduce the time during which the lighting device iscontinuously turned on compared to the previous embodiment.

FIG. 23 illustrates a further example of the control method at the timeof the continuous generation of knock signals.

According to this embodiment, when knock inputs are repeatedly appliedat time intervals equal to or less than 600 ms, only the first two knockinputs are recognized as normal knock inputs. In other words, thelighting device is turned on for 10 seconds by the two normal knockinputs, and knock input signals which are applied while the lightingdevice is turned on may be ignored.

According to this embodiment, it is possible to prevent the lightingdevice from being activated for a longer time than necessary and toprevent the lighting device from being repeatedly turned on and off whennot necessary. However, since this case does not need knock off input,the lighting device may be maintained in the state of being turned onfor a predetermined time when the lighting device is turned on.Accordingly, for example, in the case of a series of actions whereby auser performs knock on input, opens the door to take out a desiredobject, and then closes the door within, for example, 5 seconds, aproblem whereby the lighting device is activated for a longer time thannecessary may occur.

Nevertheless, this embodiment is able to control the lighting device ina very simple and easy manner even when knock on input is repeatedlyapplied, and is able to prevent the deterioration of durability due tofrequently turning on and off the lighting device.

MODE FOR INVENTION

Various embodiments have been described in the best mode for carryingout the invention.

INDUSTRIAL APPLICABILITY

The present invention provides a refrigerator equipped with a door foropening and closing a storage compartment, which is at least partiallytransparent so as to make the interior of the storage compartmentvisible without having to open the door.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1-30. (canceled)
 31. A method for controlling a refrigerator comprising: receiving a knock input on a front surface of a panel assembly of a door; detecting, at a sensor device, the knock input, wherein a portion of the sensor device is provided at a rear side of the front surface of the panel assembly; in response to the sensor device detecting the knock input, turning on a lighting device such that an inner space behind the panel assembly is viewable through the panel assembly when the door is closed.
 32. The method of claim 31, further comprising turning off the lighting device after a predetermined period of time from when the sensor device detects the knock input.
 33. The method of claim 31, wherein the panel assembly includes a front panel configured to allow passage of light emitted from the lighting device when the door is closed, wherein the front panel includes a first area through which the light from the lighting device passes and a second area disposed outside the first area to block transmission of light therethrough, and the portion of the sensor device is provided behind the second area of the front panel of the panel assembly.
 34. The method of claim 33, wherein the sensor device comprises a microphone configured to detect sound waves from the knock input on the front panel of the panel assembly.
 35. The method of claim 34, wherein the sensor device comprises an accommodation part in contact with the second area of the front panel of the panel assembly and to receive the microphone.
 36. A method for controlling a refrigerator comprising detecting, at a sensor device, vibrations or sound waves on a front surface of a panel assembly of a door, wherein a portion of the sensor device is provided at a rear side of the front surface of the panel assembly; determining whether the detected vibrations or sound waves corresponds to two knock inputs in a predetermined interval; in response to the sensor device detecting the two knock inputs in the predetermined interval, turning on an lighting device such that an inner space behind the panel assembly is viewable when the door is closed.
 37. The method of claim 36, further comprising turning off the lighting device after a predetermined period of time from when the sensor device detects the two knock inputs.
 38. The method of claim 36, wherein the panel assembly includes a front panel configured to allow passage of light emitted from the lighting device when the door is closed, wherein the front panel includes a first area through which the light from the lighting device passes and a second area disposed outside the first area to block transmission of light therethrough, and the portion of the sensor device is provided behind the second area of the front panel of the panel assembly.
 39. The method of claim 38, wherein the sensor device comprises a microphone configured to detect the generated sound waves.
 40. The method of claim 39, wherein the sensor device comprises an accommodation part in contact with the second area of the front panel of the panel assembly and to receive the microphone.
 41. A method for controlling a refrigerator comprising a main door, a door storage provided in the main door, a sub door rotatable with respect to the main door and covering the door storage at a front side of the door storage, the method comprising: detecting, at a sensor device, vibrations or sound waves on a front surface of a panel assembly of the sub door, wherein a portion of the sensor device is provided at a rear side of the front surface of the panel assembly; determining whether the detected vibrations or sound waves correspond to two knock inputs in a predetermined interval; and in response to the sensor device detecting the two knock inputs in the predetermined interval, turning on an lighting device such that the door storage behind the panel assembly is viewable when the sub door is closed.
 42. The method of claim 41, further comprising turning the lighting device off after a predetermined period of time from when the sensor device detects the two knock inputs.
 43. The method of claim 41, wherein the panel assembly includes a front panel configured to allow passage of light emitted from the lighting device when the sub door is closed, wherein the front panel includes a first area through which the light from the lighting device passes and a second area disposed outside the first area to block transmission of light therethrough, and the portion of the sensor device is provided behind the second area of the front panel of the panel assembly.
 44. The method of claim 43, wherein the sensor device comprises a microphone configured to detect the sound waves.
 45. The method of claim 44, wherein the sensor device comprises an accommodation part in contact with the second area of the front panel of the panel assembly and to receive the microphone.
 46. A method for controlling a refrigerator that comprises a cabinet with an inner space, and a door to cover the inner space and including a panel assembly, the panel assembly including a vacuum insulation space, the method comprising receiving a knock input on a front surface of the panel assembly of the door; detecting, at a sensor device, the knock input, wherein a portion of the sensor is provided at a rear side of the front surface of the panel assembly; in response to the sensor device detecting the knock input, turning on a lighting device such that an inner space behind the panel assembly is viewable through the vacuum insulation space of the panel assembly when the door is closed.
 47. The method of claim 46, further comprising turning the lighting device off after a predetermined period of time from when the sensor device detects the knock input.
 48. The method of claim 47, wherein the panel assembly includes: a first insulation panel, a second insulation panel disposed behind the first insulation panel, a seal provided between the first insulation panel and the second insulation panel such that the seal, the first insulation panel and the second insulation panel provide the vacuum insulation space; and a spacer disposed in the insulation space between the first insulation panel and the second insulation panel.
 49. The method of claim 48, wherein the panel assembly includes a hole provided in the first insulation panel, and a plug configured to block the hole.
 50. The method of claim 46, wherein the panel assembly includes a front panel disposed in front of the first insulation panel, and wherein the first insulation panel defines the front surface of the panel assembly of the door.
 51. The method of claim 50, wherein the front panel includes a first area through which the light from the lighting device passes and a second area disposed outside the first area to block transmission of light therethrough, and the portion of the sensor device is provided behind the second area of the front panel of the panel assembly. 